title: Greco-Italian War

text: In 1936 General Alberto Pariani had been appointed Chief of Staff of the army, and had begun a reorganisation of divisions to fight "wars of rapid decision", according to thinking that speed, mobility and new technology could revolutionise military operations. In 1937, three-regiment (triangular) divisions began to change to two-regiment (binary divisions), as part of a ten years plan to reorganise the standing army into twelve mountain, three motorised and three armoured divisions. The effect of the change was to increase the administrative overhead of the army, with no corresponding increase in effectiveness, as the new technology of tanks, motor vehicles, and wireless communications was slow to arrive and was inferior to that of potential enemies. The dilution of the officer class by the need for extra unit staffs was made worse by the politicisation of the army and the addition of Blackshirt Militia. The reforms also promoted frontal assaults to the exclusion of other theories, dropping the previous emphasis on fast mobile warfare backed by artillery.


title: Greco-Italian War

text: Prior to the invasion Mussolini let and go home for the harvest. There were supposed to be 1,750 lorries used in the invasion but only 107 arrived. The possibility that Greek officials situated in the front area could be corrupted or would not react to an invasion proved to be mostly wishful thinking, used by Italian generals and personalities in favor of a military intervention; the same was true for an alleged revolt of the Albanian minority living in Chameria, located in the Greek territory immediately behind the boundary, which would break out after the beginning of the attack.


title: Greco-Italian War

text: On the eve of 28 October 1940, Italy's ambassador in Athens, Emanuele Grazzi, handed an ultimatum from Mussolini to Metaxas. It demanded free passage for his troops to occupy unspecified strategic points inside Greek territory. Greece had been friendly towards Nazi Germany, profiting from mutual trade relations, but now Germany's ally, Italy, intended to invade Greece. Metaxas rejected the ultimatum with the words "" (French for "then it is war."). In this, he echoed the will of the Greek people to resist, a will that was popularly expressed in one word: ""ochi"" (Greek for "no"). Within hours, Italy attacked Greece from Albania. The outbreak of hostilities was first announced by Athens Radio early in the morning of 28 October, with the two-sentence dispatch of the general staff,


title: Greco-Italian War

text: In 1936, the 4th of August Regime came to power in Greece, under the leadership of Ioannis Metaxas. Plans were laid down for the reorganization of the Greek armed forces, including building the "Metaxas Line'", a defensive fortification along the Greco-Bulgarian frontier. Large sums of money were spent to re-equip the army but due to the increasing threat of and the eventual outbreak of war, the most significant foreign purchases from 1938 to 1939, were only partly delivered or not at all. A massive contingency plan was developed and great amounts of food and equipment were stockpiled in many parts of the country as a precaution in the event of war. After the Italian occupation of Albania in spring 1939, the Greek General Staff prepared the "IB" (Italy-Bulgaria) plan, anticipating a combined offensive by Italy and Bulgaria. Given the overwhelming superiority of such an alliance in manpower and matériel, the plan prescribed a purely defensive strategy, including the gradual retreat of the Greek forces in Epirus to the Arachthos River–Metsovo–Aliakmon River–Mt. Vermion line, to gain time for the completion of mobilization.


title: Greco-Italian War

text: With the completion of partial mobilization of the frontier formations, the plan was revised with variants "IBa" (1 September 1939) and "IBb" (20 April 1940). These modified the role of the main Greek force in the region, the 8th Infantry Division (Major-General Charalambos Katsimitros). Plan "IB" foresaw it covering the left flank of the bulk of the Greek forces in western Macedonia, securing the Metsovon pass and blocking entry into Aetolia-Acarnania, "IBa" ordered the covering of Ioannina and the defence of the Kalamas river line. Katsimitros had discretion to choose the defensive line and chose the Kalpaki line, which lay astride the main invasion axis from Albania and allowed him to use the Kalamas swamps to neutralize the Italian tank threat. The Greek General Staff remained focused on Bulgaria as its main potential enemy: of the 851 million drachmas spent on fortification between April 1939 and October 1940, only 82 million went to the Albanian frontier and the rest on the Metaxas Line and other works in the north-east.


title: Greco-Italian War

text: Nevertheless, given the enormous numerical and material superiority of the Italian military, the Greek leadership, from Metaxas down, was reserved and cautious, with few hopes of outright victory in a conflict with Italy. The General Staff's plan for the defence of Epirus envisaged withdrawal to a more defensible line, and it was only through Katsimitros' insistence that the Italian attack was confronted close to the border. Metaxas himself, during a briefing of the press on 30 October 1940, reiterated his unshakeable confidence on the ultimate victory of Britain, and hence of Greece, but was less confident on the short-term prospects, noting that "Greece is not fighting for victory. It is fighting for glory. And for its honour. ... A nation must be able to fight, if it wants to remain great, even with no hope of victory. Just because it has to." On the other hand, this pessimism was not shared by the population at large, whose enthusiasm, optimism, and the almost religious indignation at the torpedoing of "Elli", created an élan that helped transform the conflict in Greece's favour. As late as March 1941, when the German intervention was looming, an Italian officer summed up the Greeks' attitude for Mussolini with the words of a captured Greek officer: "we are sure that we will lose the war, but we will give you the spanking you need".


title: Greco-Italian War

text: In the Epirus sector, the XXV "Ciamuria" Corps consisted of the 23rd Infantry Division "Ferrara" and auxiliary troops), the 51st Infantry Division "Siena" and and the 131st Armored Division "Centauro" and tanks, of which only In addition, it was reinforced by cavalry units in a brigade-level command operating on the extreme Italian right along the coast and The XXV Corps comprised battalions, three cavalry regiments, batteries and Along with Blackshirt battalions and auxiliary troops, it numbered XXVI "Corizza" Corps in the Korçë area comprised the 29th Infantry Division "Piemonte" and and the 49th Infantry Division "Parma" and In addition, the Corps comprised the 19th Infantry Division "Venezia" and moving south from its deployment along the Yugoslav frontier between Lake Prespa and Elbasan, and was later reinforced with the 53rd Infantry Division "Arezzo" and around Shkodër. XXVI Corps totalled battalions, about ten tanks and two cavalry companies, for a total of men. The 3rd Alpine Division "Julia" with and was placed between the corps to cover the advance of XXV Corps along the Pindus mountains. The "Regia Aeronautica" had available for operations against Greece.


title: Greco-Italian War

text: About half of the fighter force consisted of 64 Fiat CR.42 "Falco" (Hawk) and 23 Fiat CR.32 "Freccia" (Arrow) biplanes (the latter already outdated). More modern and effective were the fifty Fiat G.50bis, Italian first all-metal fighters, available at the opening of the hostilities. Sixty CANT Z.1007s "Alcione" (Halcyon) represented the bulk of the Italian bomber force. Of wooden construction, these three-engined aircraft could endure a lot of punishment and were highly manoeuvrable. Other trimotors were also based on Albanian airfields: 72 Savoia-Marchetti SM.81 "Pipistrello" (Bat), a veteran of Spanish War, with fixed undercarriage, and 31 Savoia-Marchetti SM.79 "Sparviero" (Sparrowhawk) built with steel tubes, timber, aluminium, and fabric and carrying scarce defensive firepower.


title: Greco-Italian War

text: On 28 October, the Greek army had divisions, one cavalry division and three infantry brigades, all at least partly mobilized since August; four infantry divisions and two brigades were on the border with Albania; five infantry divisions faced Bulgaria and five more with the cavalry division were in general reserve. Greek army divisions were triangular and held up to more infantry than the Italian binary divisions, with slightly more medium artillery and machine-guns but no tanks. Most Greek equipment was still of First World War issue, from countries like Belgium, Austria, Poland and France, all of which were under Axis occupation, cutting off the supply of spare parts and ammunition. Many senior Greek officers were veterans of a decade of almost continuous warfare, including the Balkan Wars of 1912–13, the First World War, and the Greco-Turkish War of 1919–22.


title: Greco-Italian War

text: In Epirus, the 8th Infantry Division was already mobilized and reinforced with a regiment and the staff of the 3rd Infantry Brigade, fielding battalions and batteries. At the time of the Italian attack, the 2/39 Evzone Regiment was moving north from Missolonghi to reinforce the division. The western Macedonia sector was held by the Western Macedonia Army Section (TSDM), based at Kozani (Lieutenant-General Ioannis Pitsikas), with the II Army Corps (Lieutenant-General Dimitrios Papadopoulos) and III Army Corps (Lieutenant-General Georgios Tsolakoglou), each of two infantry divisions and an infantry brigade. The total forces available to TSDM on the outbreak of war consisted of battalions and batteries (seven heavy). The Pindus sector was covered by the "Pindus Detachment" () (Colonel Konstantinos Davakis) with two battalions, a cavalry company and batteries.


title: Greco-Italian War

text: The Royal Hellenic Air Force (, RHAF) had to face the numerically and technologically superior "Regia Aeronautica". It comprised bombers, nine reconnaissance aircraft, about aeroplanes and cooperation aircraft. It consisted of the 21st, 22nd, 23rd and 24th pursuit squadrons, the 31st, 32nd, 33rd bomber squadrons, the 1st, 2nd, 3rd, 4th military cooperation squadrons, the 2828 Independent Military Cooperation Flight and the 11th, 12th and 13th naval cooperation squadrons. At the outbreak of the war the operational combat fleet of the Greek Air Force counted 24 PZL P.24 and nine Bloch MB.151 fighters, as well as eleven Bristol Blenheim Mk IV, ten Fairey Battle B.1 and eight Potez 633 B2 bombers. Serviceable ground attack and naval support aircraft included about nine Breguet 19 two-seater biplane bombers, 15 Henschel Hs 126 reconnaissance and observation aircraft, 17 Potez 25A observation aircraft, nine Fairey III amphibious reconnaissance aircraft, 12 Dornier Do 22G torpedo bombers, and 9 Avro Anson maritime reconnaissance aircraft. The main air bases were located in Sedes, Larissa, Dekeleia, Faleron, Eleusis, Nea Anchialos and Maleme.


title: Greco-Italian War

text: The Royal Hellenic Navy had the elderly cruiser , two modern destroyers, four slightly older Italian destroyers and four obsolete s. There were six old submarines, fifteen obsolete torpedo boats and about thirty other auxiliary vessels.


title: Greco-Italian War

text: On 22 October 1940, six days before the Italian invasion of Greece, despite the Italian invasion of Egypt, the RAF Air Officer Commanding-in-Chief Middle East in Cairo was ordered to prepare squadrons for Greece, based on Ultra decodes and other sources that an Italian invasion of Greece was imminent. The RAF first sent 30 Squadron, consisting of one flight of Blenheim IF night fighters and one flight of Blenheim I light bombers, that were based at Athens-Eleusis airfield. Soon afterwards, six Vickers Wellington medium bombers were detached from 70 Squadron and a flight of Blenheim Is from 84 Squadron arrived. All RAF assets were placed under the command of Air vice-marshal John D'Albiac. The RAF aircraft participated in the Greek counter-offensive that began on 14 November, with No. 84 Squadron operating forward from Menidi. A few days later, the Gloster Gladiator fighters of 80 Squadron moved forward to Trikala, causing significant losses to the "Regia Aeronautica". 211 Squadron with Blenheim Is, followed before the end of November, joining 84 Squadron at Menidi and 80 Squadron moved to Yannina, about from the Albanian border. In the first week of December, 14 Gladiators were transferred from the RAF to the RHAF.


title: Greco-Italian War

text: The Greek commander-in-chief, Alexandros Papagos, in his memoirs regarded the second phase as ending on 28 December 1940; as the historian Ioannis Koliopoulos comments, this seems more appropriate, as December marked a watershed in the course of the war, with the Greek counter-offensive gradually grinding to a halt, the German threat becoming clear, and the beginning of British attempts to guide and shape Greek strategy. According to Koliopoulos, the final three months of the war were militarily of little significance as they did not alter the situation of the two combatants, but were mostly dominated by the diplomatic and political developments leading up to the German invasion.


title: Greco-Italian War

text: Italian forces invaded Greece in several columns. On the extreme Italian right, the coastal group moved south in the direction of Konispol with the final aim of capturing Igoumenitsa and thence driving onto Preveza. In the central sector, the "Siena" Division moved in two columns onto the area of Filiates, while the "Ferrara" Division moved in four columns against the main Greek resistance line at Kalpaki with the aim of capturing Ioannina. On the Pindus sector, the "Julia" Division launched five columns aiming to capture Metsovo and cut off the Greek forces in the Epirus sector from the east. With the onset of the Italian offensive, Papagos, until then the Chief of the Hellenic Army General Staff, was appointed commander-in-chief of the newly established General Headquarters. The Army General Staff, which functioned as the main field staff throughout the war, was handed over to Lieutenant-General Konstantinos Pallis, recalled from retirement. With Bulgarian neutrality assured—following the terms of the Balkan Pact of 1935, the Turks threatened to intervene on Greece's side if the Bulgarians attacked Greece—the Greek high command was free to throw the bulk of its army against Italian forces in Albania. Almost half the forces assigned to the Bulgarian front (13th and 17th Divisions, 16th Infantry Brigade) and the entirety of the general reserve (I Army Corps with 2nd, 3rd, and 4th Infantry Divisions, as well as the Cretan 5th Infantry Division and the Cavalry Division) were directed to the Albanian front.


title: Greco-Italian War

text: On the Epirus sector, Katsimitros had left five battalions along the border to delay the Italian advance, and installed his main resistance line in a convex front with the Kalpaki pass in the centre, manned by nine battalions. Further two battalions under Major-General Nikolaos Lioumbas took over the coastal sector in Thesprotia. The swamps of the Kalamas river, especially before Kalpaki, formed a major obstacle not only to armoured formations, but even to the movement of infantry. A further battalion and some artillery were detached to the Preveza area in the event of an Italian landing, but as this did not materialize, they were swiftly moved to reinforce the coastal sector. By the night of 29/30 October, the Greek covering units had withdrawn to the Kalpaki line, and by 1 November, Italian units made contact with the Greek line. During these three days, the Italians prepared their assault, bombarding the Greek positions with aircraft and artillery. In the meantime, the developing Italian threat in the Pindus sector forced Papagos to cable Katsimitros that his main mission was to cover the Pindus passes and the flanks of the Greek forces in western Macedonia, and to avoid offering resistance if it left his forces depleted. Katsimitros had already decided to defend his line, however, and disregarded these instructions, but detached some forces to cover its right along the Aoös River. On 1 November, the Italians managed to capture Konitsa and the "Comando Supremo" gave the Albanian front priority over Africa.


title: Greco-Italian War

text: The scheduled Italian amphibious assault on Corfu did not materialize due to bad weather. The Italian navy commander, Admiral Domenico Cavagnari, postponed the landing to 2 November, but by that time Visconti Prasca was urgently demanding reinforcements, and Mussolini ordered that the 47th Infantry Division "Bari", earmarked for the operation, be sent to Albania instead. Mussolini proposed a landing at Preveza on 3 November to break the emerging impasse, but the proposal met with immediate and categorical refusal by the service chiefs.


title: Greco-Italian War

text: The main Italian attack on the Kalpaki front began on 2 November. An Albanian battalion, under the cover of a snowstorm, managed to capture the Grabala heights, but were thrown back by a counterattack on the next day. On the same day, an attack spearheaded by 50–60 tanks against the main Kalpaki sector was also repulsed. The Greek units east of the Kalamas were withdrawn during the night. On 5–7 November, repeated assaults were launched against the Grabala and other heights; on the night of the 7th, Grabala briefly fell once more, but was swiftly recaptured. On 8 November, the Italians began withdrawing and assuming defensive positions until the arrival of reinforcements. On the coastal sector, the Italians made better progress. The Greek covering units were forced south of the Kalamas already on the first day, but the bad state of the roads delayed the Italian advance. On the night of 4/5 November, the Italians crossed the river and broke through the defences of the local Greek battalion, forcing Lioumbas to order his forces to withdraw south of the Acheron River. Igoumenitsa was captured on 6 November, and on the next day, the Italians reached Margariti. This marked their deepest advance, as the Thesprotia Sector began receiving reinforcements from Katsimitros, and as on the other sectors the situation had already turned to the Greeks' favour.


title: Greco-Italian War

text: As evidence of the Italian offensive's failure mounted, on 8 November, Visconti Prasca was relieved of overall command in Albania and relegated to command the Italian forces in the Epirus front, while General Ubaldo Soddu, State Undersecretary of War, assumed his place. Soddu's report from Albania underlined Greek resistance in Epirus and the mounting threat of the Greek concentration in western Macedonia, and recommended taking up defensive positions "while awaiting the reinforcements that would permit us to resume action as soon as possible". Mussolini consented. With the Italians on the defensive, 8th Division began launching local counterattacks to regain the lost ground. By 13 November, the Greek forces once again stood at the Kalamas river along its entire length. On 12 November, I Army Corps under Lieutenant-General Panagiotis Demestichas took over the Epirus sector. 8th Division was subordinated to it, while the coastal sector was placed under the independent Lioumbas Detachment.


title: Greco-Italian War

text: A greater threat to the Greek positions was posed by the advance of the 3rd Alpine Division "Julia", under Mario Girotti, over the Pindus Mountains towards Metsovo, which threatened to separate the Greek forces in Epirus from those in Macedonia. The opposing Greek force, the Pindus Detachment, numbered 2,000 men, was formed of reservists of the 51st Regiment, mobilized on 29 August, while one of its three battalions (III/51) was formed as late as 15 October and was still on its way to the front. Colonel Davakis and his men had to cover a front some 37 km in width, and moreover over extremely broken terrain. The Italian attack began under torrential rainfall and made rapid progress, forcing the Greeks to abandon their forward posts, especially in the Detachment's central sector. Davakis was forced to deploy the companies of the III/51 Battalion piecemeal as soon as they arrived, leaving himself with no reserves.


title: Greco-Italian War

text: The situation worried the TSDM, which began sending whatever reinforcements it could muster, and assigned the Pindus sector to the 1st Infantry Division. Despite the onset of snowfall on the 29th, the "Julia" Division continued pressing its attack on the Greek centre and left during 29–30 October, forcing the Greeks to withdraw towards Samarina. From 30 October, however, the Greeks managed to stabilize the situation. Command in the Pindus sector passed to 1st Division and Major-General Vasileios Vrachnos, while additional forces—the Cavalry Division, 5th Brigade, and he newly formed Cavalry Brigade—were deployed on the flanks of the Italian salient and in the rear to secure the vital passes.


title: Greco-Italian War

text: After covering of mountain terrain in icy rain, the "Julia" Division captured the village of Vovousa, on 2 November, but failed to reach its primary objective; Metsovo, south. That same day, Davakis was gravely wounded during a reconnaissance mission near Fourka. However, it had become clear to the Italians that they lacked the manpower and the supplies to continue in the face of the arriving Greek reserves. On 3 November, the Italian spearhead was surrounded from all sides. The commander of the "Julia" Division requested from the Italian headquarters relief attacks and Italian reserves were thrown into the battle. Thus, Visconti Prasca sent forward the "Bari" Division to its aid, but it was unable to reach the cut-off Italian forces. In the meantime, the assistance of the local civilians, including men, women, and children, to the Greek forces proved invaluable. As a result of the Greek pressure the "Julia" Division was virtually wiped out, while the villages previously taken by the Italians were recaptured on 3 and 4 November. Within less than a week, the remaining Italian troops in this sector were in roughly the same positions they occupied before the declaration of the war. By 13 November the Greek forces had completed the re-occupation of the Grammos and Smolikas mountain ranges. On the same day, Visconti Prasca was relieved and recalled to Italy.


title: Greco-Italian War

text: By 14 November, the Italian forces in Albania had been reorganized in two field armies: the Ninth Army, formed out of the XXVI Corps in the Korçë sector, comprising five infantry and two alpine divisions with elite Alpini troops as well as a number of independent regiments, including Blackshirt and Albanian battalions; and the Eleventh Army (former XXV Corps) on the Epirus sector, with three infantry, an armoured, and a cavalry division, as well as a number of independent units. The Italian situation was very difficult, as the troops on the front had been fighting non-stop for three weeks and were exhausted. The supply situation was abysmal, with the army lacking lorries, horses, and mules; the limited capacity of Albania's two main ports, Valona and Durrës, created a bottleneck for supplies and reinforcements, while the airlift initiated between Italy and Tirana—which consumed all of the Italian Air Force's transport capacity to the detriment of Africa—could transport troops, but not heavy equipment. The Greek order of battle on 14 November consisted of Lieutenant-General Demestichas' I Corps on the coastal sector (2nd, 8th, and the Cavalry Divisions, and the Lioumbas Detachment), Lieutenant-General Papadopoulos' II Corps in the Pindus sector (1st Infantry Division, 5th Brigade and the Cavalry Brigade), and Lieutenant-General Tsolakoglou's III Corps in western Macedonia (9th, 10th, 15th Infantry Divisions, with 11th Division assembling in its rear). The latter two corps were under the command of TSDM, led by Lieutenant-General Pitsikas. The 3rd, 4th, and 5th Infantry Divisions, as well as the 16th Brigade, were kept in reserve. By 12 November, Papagos had over battalions on familiar terrain against fewer than fifty Italian battalions.


title: Greco-Italian War

text: From the first days of November, III Corps had undertaken limited advances into Albanian territory, and already on 6 November, it submitted plans for a general offensive. Judging it too ambitious for the moment, Papagos postponed the offensive for 14 November. III Corps' main objective was the capture of the Korçë plateau, which controlled access to the interior of Albania along the valley of the Devoll river. The plateau lay behind the Morava and Ivan mountains on the Greco-Albanian frontier, which were held by the 29th "Piemonte", the 19th "Venezia", and the 49th "Parma" divisions. The Italians were later reinforced by the 2nd Alpine Division "Tridentina", the 53rd Infantry Division "Arezzo", and 30–50 tanks of the "Centauro" Division. Leaving five battalions to secure its rear, III Corps attacked with twenty battalions and 37 artillery batteries. Due to the lack of tanks or anti-tank weapons to counter Italian armour, the Greeks decided to limit their movement along the mountain ridges, never descending to the valleys. The offensive was launched on the morning of 14 November, with the corps' three divisions moving on converging lines of attack towards Korçë. To achieve surprise, the attack was not preceded by an artillery barrage.


title: Greco-Italian War

text: The Italian forces were indeed taken by surprise, allowing the Greeks to force several breaches in the Italian positions on 14–16 November. On 17 November, III Corps was reinforced with 13th Division, and on the next day, with 11th Division, which along with the 10th Division formed a new command, the "K" Group of Divisions or OMK (Lieutenant-General Georgios Kosmas). The most critical moment for the Greeks came on 18 November, when elements of the 13th Division panicked during an ill-coordinated attack and the division almost retreated; its commander was sacked on the spot and the new commander, Major-General Sotirios Moutousis, forbade any further retreat, restoring the front. On 19–21 November, the Greeks captured the summit of Morava. Fearing that they would be surrounded and cut off, the Italians retreated towards the Devoll valley during the night, and on 22 November the city of Korçë was captured by 9th Division. By 27 November, TSDM had captured the entire Korçë plateau, suffering 624 dead and 2,348 wounded. Further south and west, I and II Corps had moved to evict the Italians from Greek territory, which they achieved by 23 November. II Corps further moved across the border line, capturing Ersekë on 21 November and Leskovik on the next day. On 23 November, bowing to pressure from Badoglio and Roatta, Mussolini finally reversed his early October order for demobilization.


title: Greco-Italian War

text: Following the capture of Korçë and the eviction of the Italian forces from Greek soil, the Greek GHQ faced two options: continue the offensive in the Korçë sector in the direction of Elbasan or shift focus on the left flank and drive towards the port of Valona. The latter was chosen, as the capture of Valona would be of great strategic significance, leaving the Italians with only Durrës as an entry port. TSDM, comprising III Corps and OMK, would defend their positions on the Greek right and apply pressure, while I Corps would move north along the Gjirokastër–Tepelenë–Valona axis. II Corps would form the pivot of the movement, securing the connection between I Corps and TSDM, advancing in step with its western neighbour in the direction of Berat. I Corps was reinforced with 3rd Division (21 November) and II Corps with 11th Division (27 November) and the Cavalry Division (28 November).


title: Greco-Italian War

text: Between 24 and 30 November, I Corps moved north into Albania along the Drinos river, while II Corps moved in the direction of Frashër, which it captured in early December. TSDM continued to apply pressure against the Italians and the 10th Division captured Moscopole on 24 November. Pogradec was captured unopposed by the 13th Division on 30 November. The continued Greek advance caused another crisis in the Italian hierarchy. The news of the fall of Pogradec and the pessimistic reports of the Italian commanders in Albania reportedly caused Mussolini to consider asking for a truce through the Germans but in the end he recovered his nerve and ordered Soddu to hold fast. The Greeks would be worn out, since they had "... no war industry and can only count on supplies from Great Britain". Mussolini, encouraged by the hardline Fascist Party secretary Roberto Farinacci, sacked Badoglio on 4 December and replaced him with Ugo Cavallero as Chief of the General Staff. The resignation of the governor of the Italian Dodecanese, Cesare Maria De Vecchi and Admiral Cavagnari, followed within a few days.


title: Greco-Italian War

text: I Corps captured Delvinë on 5 December and Gjirokastër on 8 December; the Lioumbas Detachment captured Sarandë— renamed Porto Edda after Edda Mussolini—on 6 December. Further east, the 2nd Division captured the Suhë Pass after a fierce struggle from 1–4 December, while 8th Division launched repeated attacks on the heights around the Kakavia Pass, forcing the Italians to withdraw on the night of 4/5 December. The division had suffered considerable losses but took over 1,500 prisoners, several artillery pieces and thirty tanks. In the TSDM sector, Lieutenant-General Kosmas (in command of the "K Group", essentially the 10th Division) captured the Ostravicë Mountain on 12 December, while III Corps—since 1 December reinforced with 17th Division, which replaced 13th Division—completed its occupation of the Kamia massif and secured Pogradec.


title: Greco-Italian War

text: On 2 December, Papagos, and Crown Prince Paul, visited the front. Pitsikas and Tsolakoglou urged him to order an immediate attack on the strategic Klisura Pass, without waiting for I and II Corps to level with TSDM. Papagos refused and ordered the plan to continue, with III Corps relegated to a passive role. (This decision was later criticized, coupled with the onset of winter, it immobilised the Greek right wing. Despite the atrocious weather and the heavy snowfall, the Greek offensive continued on the left throughout December. I Corps, now comprising 2nd, 3rd and 4th Divisions (8th Division and the Lioumbas Detachment were moved back into reserve) captured Himarë on 22 December. II Corps, moving between the Aöos and the Apsos rivers, reached the vicinity of Klisura, but failed to capture the pass. To its right, the V Army Corps (the former "K Group" but still comprising only the 10th Division) managed to advance up to Mount Tomorr and secure the connection between II and III Corps, which remained in their positions.


title: Greco-Italian War

text: On 28 December 1940, the Greek GHQ took the decision to halt large-scale offensive operations in view of the stiffening Italian resistance, the worsening supply situation and the bad weather, which "inter alia" led to a large number of frostbite casualties. This decision took effect on 6 January, whereby only local offensive operations would take place to improve Greek lines until the weather improved. The Italians had eleven infantry divisions, (11th Infantry Division "Brennero", 19th Infantry Division "Venezia", 23rd Infantry Division "Ferrara", 29th Infantry Division "Piemonte", 33rd Infantry Division "Acqui", 37th Infantry Division "Modena", 48th Infantry Division "Taro", 49th Infantry Division "Parma", 51st Infantry Division "Siena", 53rd Infantry Division "Arezzo", and 56th Infantry Division "Casale") and four Alpine divisions (2nd Alpine Division "Tridentina", 3rd Alpine Division "Julia", 4th Alpine Division "Cuneense", and 5th Alpine Division "Pusteria") and the 131st Armored Division "Centauro", with the 6th Infantry Division "Cuneo" and the 7th Infantry Division "Lupi di Toscana" moving to the front. There were also two independent Bersaglieri regiments, a grenadier regiment, two cavalry regiments, Blackshirt and Albanian battalions and other units. According to official Italian documents, on 1 January 1941, Italy had 10,616 officers, 261,850 men, 7,563 vehicles, and 32,871 animals in Albania. This strengthening of the Italian position prompted Cavallero, who after Soddu's recall on 29 December combined his post as Chief of the General Staff with the overall command in Albania, to pronounce that the "period of crisis [was] almost overcome" and to begin planning for an attack aiming to recapture Korçë in early February.


title: Greco-Italian War

text: The main operation envisaged by the Greek GHQ was the capture of the Klisura Pass by II Corps, coupled with minor offensives by I Corps and TSDM to improve their positions. II Corps attacked on 8 January, with 1st Division on the left and 15th Division, followed by the 11th Division, on the right flank. The 15th Division faced the "Julia" Division, and after a hard struggle managed to capture its positions in a costly success. The 11th Division followed up on 9 January next day captured the pass. The offensive forced Cavallero to deploy the reserves he had husbanded for the Korçë offensive, which never took place. The newly arrived "Lupi di Toscana" division was routed. The division went into action on 9 January to support the "Julia" Division, after a 24-hour forced march in horrendous weather, without having time to reconnoitre the front, without maps and without coordinating fire support with the "Julia" Division. The commander and the chief of staff failed to coordinate its two regiments, which became entangled on the same mule track. Despite attacking downhill and facing a numerically inferior enemy, the division lost a battalion to encirclement and were driven back to their starting positions after two days. By 16 January, the division had disintegrated and "ceased to exist as an organized force", with only 160 officers and men immediately available and over 4,000 casualties. On 26 January, the Italians counter-attacked to recover the pass but II Corps, reinforced with 5th Division, managed to repel them and then counter-attacked. In the Battle of Trebeshina, a series of engagements from 2–12 February, the Trebeshinë massif was captured. The capture of the strategic Klisura pass by the Greek army was considered a major success by the Allied forces, with the Commander of the British forces in the Middle East, Archibald Wavell, sending a congratulatory message to Alexander Papagos.


title: Greco-Italian War

text: As the threat of a German invasion from Bulgaria increased, the need to transfer Greek divisions to the Bulgarian frontier forced Papagos to launch a final effort to capture Valona as quickly as possible. The RAF agreed to challenge the air superiority of the "Regia Aeronautica", which had recovered with the loss of much of the RHAF in ground-attack operations, rather than continue ineffective attempts at interdiction. With reinforcements from Egypt and the drying of a landing-ground at Paramythia, the RAF managed support sorties by the end of February. Launched in mid-February, the attack saw I Corps gain ground towards Tepelenë; Italian resistance and a deterioration in the weather forced a suspension of operations before Tepelenë, let alone Valona or Berat, were reached. The Italian defensive success was costly, and signs of an imminent Italian offensive in the central sector of the front forced a return to the defensive.


title: Greco-Italian War

text: By early February 1941, the Greek Army was down to less than two months of artillery ammunition overall and had shortages in every area of material, while the Italians possessed ample reserves, endangering their position. The Greeks appealed to the United States for material aid,


title: Greco-Italian War

text: but the British ensured that they themselves got first priority for US production. Furthermore, there were shortages of materials and even food across the country. Continuing degradation of their logistical capability would soon mean the end of effective Greek resistance.


title: Greco-Italian War

text: British material and air support had been provided, but at this point it was "relatively small." Further British aid in March and April would only partially alleviate this problem.


title: Greco-Italian War

text: On 14 February, in view of GHQ's increasing concern with developments on the Bulgarian frontier, a new higher command, the Epirus Army Section (TSI), under Lieutenant-General Markos Drakos, was formed, comprising I and II Corps. Despite Greek success in Albania, dissension within the Greek leadership emerged over strategy towards the expected German attack and the need for a withdrawal in Albania. The front commanders in Albania represented their views to GHQ in Athens and in early March, Papagos moved to replace virtually the entire leadership in the Albanian front: Drakos, Kosmas and Papadopoulos, the commanders of TSI, I and II Corps respectively, were replaced by the TSDM commander Lieutenant-General Pitsikas, Lieutenant-General Demestichas and Major-General Georgios Bakos, TSDM being taken over by Tsolakoglou.


title: Greco-Italian War

text: On 4 March, the British sent the first convoy of Operation Lustre with "W Force" (Lieutenant-General Sir Henry Maitland Wilson) and supplies for Greece. The Italian leadership desired to achieve a success against the Greek army before the impending German intervention and reinforced the Albanian front to 28 divisions with an average of 26 serviceable bombers, 150 fighters, along with 134 bombers and 54 fighters of the 4° "Squadra" in Italy. Cavallero planned an attack on of the centre of the front, to recapture Klisura and advance towards Leskovik and Ioannina. The attack would be carried out by the VIII Army Corps (24th Infantry Division "Pinerolo", 38th Infantry Division "Puglie", and 59th Infantry Division "Cagliari"), with XXV Corps (2nd Infantry Division "Sforzesca", 47th Infantry Division "Bari", 51st Infantry Division "Siena", and 7th Infantry Division "Lupi di Toscana") as a second echelon, and the "Centauro" and "Piemonte" divisions as general reserves. The Greek units opposite them were II Corps (17th, 5th, 1st, 15th, and 11th Divisions), with three regiments as TSI's general reserve, and 4th Division providing reinforcement. II Corps continued limited offensive action as late as 8 March to improve its positions.


title: Greco-Italian War

text: The Italian attack, watched by Mussolini, began on 9 March, with a heavy artillery barrage and air bombardment; on the main sector, held by the Greek 1st Division, over 100,000 shells were dropped on a front. Despite repeated assaults and heavy shelling, the positions of 1st Division held during 9–10 March. A flanking manoeuvre on 11 March ended in Italian defeat. The exhausted "Puglie" Division was withdrawn and replaced with the "Bari" Division during the subsequent night, but all attacks until 15 March failed. The Italian offensive halted on 16–18 March, allowing the Greeks to bring reserves forward and begin a gradual reshuffle their line, relieving the 1st Division with the 17th. The Italian offensive resumed on 19 March with another attack on Height 731 (the 18th thus far). Attacks, preceded by heavy artillery bombardments, followed daily until 24 March, the last day of the Italian offensive, without achieving any result. Mussolini admitted that the result of the Italian offensive was "zero". Italian casualties amounted to over 11,800 dead and wounded, while the Greeks suffered 1,243 dead, 4,016 wounded and 42 missing in action.


title: Greco-Italian War

text: Although it failed, the Italian Spring Offensive revealed a "chronic shortage of arms and equipment" in the Greek Army. Even with British support, the Greeks were fast approaching the end of their logistical tether. British intelligence estimated that Greece's reserves, although numbering 200,000–300,000 partly-trained men on paper, could not be mobilized for lack of arms and equipment, which were being consumed by the Albanian front. By the end of March 1941, the Greek Army possessed one month's supply in various types of


title: Greco-Italian War

text: artillery ammunition. The British had already supplied, among other goods, 40 million 7.92 rounds and 150 mortars (50 51mm and 100 76mm) the previous month, but had not yet fulfilled the Greeks' mid-January request of 300,000 uniforms and sets of shoes.


title: Greco-Italian War

text: The Italians still had reserves of men and materiel, the Greek defences of Macedonia and Thrace, which would face the German attack, were left undermanned and underequipped due to the demands of the Albanian front. The Eastern Macedonia Army Section (TSAM), which manned the Metaxas Line, was left with only 70,000 men to defend against any potential German advance, though plans called for the fortifications to be held by 200,000 men. British planners disagreed with the Greek plan to hold on to the Metaxas Line, as well as the insistence of not ceding a single bit of ground to the Italians, noting that the Greek forces were insufficient to prevent or resist a German breakthrough. The Central Macedonia Army Section (TSKM), which manned the Yugoslav border, was even weaker: its three divisions were recently raised from reserves and possessed no anti-air weaponry, anti-tank weaponry, armored vehicles, or almost any motor vehicles. They had few automatic weapons and faced even shortages of basic supplies such as tents and helmets. 14 out of the 20 available divisions of the Greek army were facing the Italians on the Albanian front as part of the Epirus Army Section, totaling 33 regiments. In an effort to keep Greece in the fight, British aid drastically stepped up in March and April, which included uniforms, weapons, and ammunition of various types. However, the Greeks still did not consider this sufficient for successfully prosecuting the rest of the war.


title: Greco-Italian War

text: Though the Greek forces faced logistical difficulties their supply lines worked much better. On the other side, Italian supplies and ammunition faced critical levels even after one month of military operations. In general Italian logistics failed to keep up with the confusing movements of the Italian units, as a result they were perennially lacking essential supplies. Italian General Gabriele Nasci realized that the Greek units were far more familiar in mountain warfare and could always employ local guides and provisions, thus freeing them from concern with supply line and enable them to attack in more flexible way. Indeed the area that the conflicts took place was far more familiar to the Greek soldiers than to the Italians. The Greek side was far more familiar in mountain warfare considering also the fact that many Greeks especially those natives of Epirus were fighting for their homes. Additionally some Greek weapons were superior to their Italian counterparts: the Hotchkiss machine gun outperformed the Italian Breda and Fiat equivalent and was less liable to overheating as well as jammed less often. The Skoda 75 mm and 105mm mountain artillery of the Greek army was also superior compared to Italian mortars.


title: Greco-Italian War

text: As such at March 29, Italian General Mario Roatta, Chief of the Italian General Staff, asked for German intervention to relieve the pressure on his own formations. On the other hand just before the German intervention at April 1941, Greek, British and Yugoslav officers agreed that a joined Greek-Yugoslavian operation will lead to the final push the will and force the Italians throw the Italians into the Adriatic. Orders given by General Papagos dictated the advance of the Epirus Army towards Vlore and Berat, while the West Macedonia Army would cut the remaining Italian units located in Elbasan and Durres. Additionally, Papagos advised the Yugoslav side to advance in the direction of Durres, Kukes and Elbasan. A swift Italian defeat would free up forces that could be used for the defence of Macedonia against a German threat.


title: Greco-Italian War

text: With most of the Greek army on the Albanian border, Operation Marita began through Bulgaria on 6 April, which created a second front. Greece had received a small reinforcement from British forces based in Egypt in anticipation of the German attack, but no more help was sent after the invasion. The Greek army was outnumbered; the Bulgarian defensive line did not receive adequate troop reinforcements and was quickly overrun. The Germans outflanked the immobile Greek forces on the Albanian border, forcing the surrender of the Eastern Macedonia Field Army section in only four days. The British Empire forces began a retreat. For several days Allied troops contained the German advance on the Thermopylae position, allowing ships to be prepared to evacuate the British force. The Germans reached Athens on 27 April and the southern shore on 30 April, capturing troops. The conquest of Greece was completed with the capture of Crete a month later and Greece was occupied by the military forces of Germany, Italy, and Bulgaria until late 1944.


title: Greco-Italian War

text: On 6 April, Papagos ordered TSDM to launch an attack towards Elbasan, in conjunction with Yugoslav forces. The attack began on 7 April and the 13th Division made some progress, but the Yugoslav army, attacked by the Germans, rapidly collapsed and the operation was cancelled. On 12 April, GHQ in Athens ordered the Greek forces on the Albanian front to retreat but the decision was too late. The Greek commanders knew that Italian pressure, the lack of motor transport and pack animals, the physical exhaustion of the Greek army, and the poor transport network of Epirus meant that any retreat was likely to end in disintegration. Advice to retreat before the start of the German attack had been rejected and they petitioned Pitsikas to surrender. Pitsikas forbade such talk, but notified Papagos and urged a solution that would secure "the salvation and honour of our victorious Army". The order to retreat, the disheartening news of the Yugoslav collapse, and the rapid German advance in Macedonia led to a breakdown of morale in the Greek troops, many of whom had been fighting without rest for five months and were forced to abandon hard-won ground. By 15 April, the divisions of II Army Corps, beginning with the 5th Division, began to disintegrate, with men and even entire units abandoning their positions.


title: Greco-Italian War

text: On 16 April, Pitsikas reported to Papagos that signs of disintegration had also begun to appear among the divisions of I Corps and begged him to "save the army from the Italians" by allowing it to capitulate to the Germans, before the military situation collapsed completely. On the following day TSDM was renamed III Army Corps and placed under Pitsikas' command. The three corps commanders, along with the metropolitan bishop of Ioannina, Spyridon, pressured Pitsikas to unilaterally negotiate with the Germans. When he refused, the others decided to bypass him and selected Tsolakoglou, as the senior of the three generals, to carry out the task. Tsolakoglou delayed for a few days, sending his chief of staff to Athens to secure permission from Papagos. The chief of staff reported the chaos in Athens and urged his commander to take the initiative in a message that implied permission by Papagos, although this was not in fact the case. On 20 April, Tsolakoglou contacted Sepp Dietrich, the commander of the nearest German unit, the Leibstandarte SS Adolf Hitler (LSSAH) brigade, to offer surrender. The protocol of surrender was signed by Tsolakoglou and Dietrich at 18:00 on the same day. Presented with the fait accompli an hour later, Pitsikas resigned his command.


title: Greco-Italian War

text: Thoroughly outclassed by the far larger and more modern Italian "Regia Marina", the Royal Hellenic Navy (RHN) was unable to attempt a direct naval confrontation. Its role was rather limited to patrol and convoy escort duties, a particularly important task given the general inadequacy of the Greek transport network on land; apart from large quantities of matériel, mobilized men and over were moved by sea during the war. The RHN carried out limited operations against Italian shipping in the Strait of Otranto with submarines (losing one vessel), sinking at least of transport and merchant shipping, but lack of maintenance facilities made it impossible to continue the effort. However, the Greek submarine force was too small to be able to seriously hinder the supply lines between Italy and Albania; between 28 October 1940 and 30 April 1941 Italian ships made 3,305 voyages across the Otranto straits, carrying 487,089 military personnel (including 22 field divisions) and 584,392 tons of supplies while losing overall only seven merchant ships and one escort ship. Destroyers carried out bold but fruitless night raids on 14 November 1940, 15 December and 4 January 1941.


title: Greco-Italian War

text: The British fought the Battle of the Strait of Otranto on 12 November acting as a decoy force and the "Regia Marina" had half of its capital ships put out of action by the British Royal Navy (RN) during the Battle of Taranto but Italian cruisers and destroyers continued to escort convoys between Italy and Albania. On 28 November, an Italian squadron bombarded Corfu and on 18 December and 4 March, Italian task forces shelled Greek coastal positions in Albania. From January 1941, the main task of the RHN was to escort the convoys of Operation Excess to and from Alexandria, in co-operation with the RN. As the convoys transporting Lustre Force began in early March, the Italian Fleet sortied against them and the British were forewarned by "Ultra" decrypts. The Mediterranean Fleet intercepted the Italians at the Battle of Cape Matapan on 28 March and sank three cruisers and two destroyers, the greatest Italian naval defeat at sea of the war.


title: Greco-Italian War

text: The poor infrastructure in Albania air bases hindered communications and movements between the Italian flying units. Only two airfields – Tirana and Valona – had Macadam runways so Autumn and Winter weather made operations more difficult. There was also the usual lack of co-operation with Italian Navy and Army. Two days after the start of the war, on 30 October, there was the first air battle. Some Henschel Hs126s of 3/2 Flight of 3 Observation "Mira" took off to locate Italian Army columns. But they were intercepted and attacked by Fiat CR.42s of 393 "Squadriglia". A first Henschel was hit and crashed, killing its observer, Pilot Officer Evanghelos Giannaris, the first Greek aviator to die in the war. A second Hs 126 was downed over Mount Smolikas, killing Pilot Officer Lazaros Papamichail and Sergeant Constantine Yemenetzis.


title: Greco-Italian War

text: On 2 November, a squadron of 15 Italian CANT Z.1007 bombers, with Fiat CR.42 fighter escorts headed towards Thessaloniki and was intercepted by Greek PZL P.24 fighters of the 22nd Squadron. Second Lieutenant Marinos Mitralexis shot down one bomber and being out of ammunition, aimed the nose of his PZL P. 24 at the tail of a bomber, smashed the rudder and sent the bomber out of control. The news of Mitralexis' feat quickly spread throughout Greece and boosted morale. On 2 December, the 21st Pursuit Squadron re-equipped with 14 ex-RAF Gladiators.


title: Greco-Italian War

text: Ultra decrypts of orders to the "Regia Aeronautica" and nightly reports from in Italy to "Comando Aeronautico Albania della Regia Aeronautica" in Tirana, disclosed bombing targets for the next day and were sent to RAF HQ in Greece, to assist in fighter interception. From mid-November to the end of December, the Blenheim and Wellington bombers from Egypt flew but almost failed, due to a lack of all-weather airfields and the season, when flying was possible for about per month. The bombing effort was concentrated on Durazzo and Valona but some close support operations were carried out and the fighters near Athens helped to reduce the number of Italian raids. By the end of 1940, the Gladiator pilots had claimed shot down for the loss of six, which established a measure of air superiority over the Pindus mountains. In January 1941, 11 Squadron and 112 Squadron were sent to Greece despite being at half strength. 33 Squadron, 113 Squadron (Blenheims) and 208 Squadron (Lysanders and Hurricanes) moved in March.


title: Greco-Italian War

text: The British fighters were able to prevent most Italian air operations after mid-February, when the Greek army made a maximum effort to capture Valona. The RAF managed fifty sorties on Gladiators and Hurricanes intercepted a raid by fifty Italian aircraft on 28 February, the RAF claiming for the loss of one. When the Greek advance was slowed by more bad weather and Italian reinforcements, the RAF returned to attacks on airfields and ports. On the eve of the German invasion in April, the RAF had claimed aircraft confirmed and for a loss of four pilots and ten aircraft. RAF Greece had been increased to nine squadrons and two Wellington detachments of about of which only serviceable, in support of about and Yugoslav aircraft. RAF losses in the Greek campaign were killed, missing or prisoner and the air, and or abandoned during the evacuation.


title: Greco-Italian War

text: The war was greeted with great enthusiasm by the Greek population, in Athens crowds filled the streets with patriotic fervour, as newspapers hurried to publish their newest editions to stir up the people further. The popular story that Metaxas had defiantly told Grazzi ""ochi!"" ("no!") on the night of 28 October 1940 made the previously unpopular prime minister into a national hero. Georgios Vlachos in an editorial in his newspaper "Kathimerini" wrote: "Today there is no Greek who does not add his voice to the thunderous OCHI. OCHI, we will not hand over Greece to Italy. OCHI, Italian "ruffiani" will not set foot on our land. OCHI, the barbarians will not desecrate our Parthenon". He also wrote his famous article "The dagger" ("To stileto").


title: Greco-Italian War

text: Men in Greece rushed to volunteer for the war effort, cramming into the back of trams to get to the recruiting offices. Morale amongst the troops was as high as it could get with a universal feeling that Greece must fight, with few entertaining the idea of failure. This enthusiasm was not shared by some of the political leadership, there was a sense that Greece would lose the war but needed to fight nonetheless, Metaxas stated in a letter to Winston Churchill that "The war we confront today is thus solely a war of honour" and that "The outcome of the world war will not be decided in the Balkans."


title: Greco-Italian War

text: The popularity of Metaxas' regime would also receive a boost, with Metaxas becoming a national hero overnight, with even many left-wing and liberal Greeks who opposed Metaxas showing admiration and support for him, flocking to the cause.


title: Greco-Italian War

text: Soon, with the first victories at the front, Greek artists started to write and sing patriotic and festive songs. The reputation of Sofia Vembo skyrocketed when her performance of patriotic and satirical songs became a major inspiration for the fighting soldiers as well as the people at large for whom she quickly became a folk heroine. Another satirical popular song named "Koroido Mussolini" (Mussolini fool) was written by Nikos Gounaris in the rhythm of "Reginella Campagnola", a popular Italian song of the era.


title: Greco-Italian War

text: The announcement of the Italian attack was greeted with favour but not much enthusiasm, by the Italian public. The situation changed as the Italian attack devolved into a stalemate in early November, especially after the British Taranto raid and the start of the Greek counter-offensive. In private conversations, Italians soon took to calling the war in Albania "a second and worse Caporetto". The regime's popularity slumped further with the introduction of strict rationing in food, oil and fats in early December. Despite imposing a price freeze in July, prices rose and the state distribution network of staple foods and heating oil broke down. Coupled with the dismissal of Badoglio and the British advance in North Africa in Operation Compass, it produced "the regime's most serious crisis since the murder of Giacomo Matteotti in 1924" (MacGregor Knox). In a move designed to bolster the Fascist Party's flagging standing, in mid-January 1941 Mussolini ordered the all senior "gerarchi" and officials under 45 years, to go to the Albanian front (much to their displeasure). According to Dino Grandi at least, this move caused much resentment against Mussolini among the Party leadership that simmered underground and resulted in his dismissal in July 1943.


title: Greco-Italian War

text: On the other hand, the Greek historian Zacharias Tsirpanlis observes that while post-war Italian accounts confirm the view that "due to the Greek success Italian public opinion slowly turned against the Fascist regime, marking the beginning of the end for Mussolini", this did not yet materialize in any form of active resistance, including in the front itself. While a cynicism towards the Fascist regime and its symbols and leaders had set in, incidents of insubordination remained isolated. Indeed, according to the eyewitness account of Air Force chief Francesco Pricolo, when Mussolini made an unannounced visit to the front on 2 March 1941, the "Duce" was himself surprised by the enthusiasm with which he was greeted, having expected open hostility from the soldiers.


title: Greco-Italian War

text: In an effort to win Albanian support for Italian rule, Ciano and the Fascist regime encouraged Albanian irredentism in the directions of Kosovo and Chameria. Despite Jacomoni's assurances of Albanian support in view of the promised "liberation" of Chameria, Albanian enthusiasm for the war was distinctly lacking. The few Albanian units raised to fight alongside the Italian Army mostly "either deserted or fled in droves". Albanian agents recruited before the war, are reported to have operated behind Greek lines and engaged in acts of sabotage but these were few in number. Support for the Greeks, although of limited nature, came primarily from the local Greek populations who warmly welcomed the arrival of the Greek forces. Despite official Greek proclamations that they were fighting for the liberation of Albania, Greek claims on Northern Epirus were well-known. Albanian suspicions were reinforced, when a new municipal council of eleven Greeks and four Albanians was appointed at Korçë, and when the military governor of Gjirokastër prohibited the celebration of the Albanian independence day on 28 November (his counterpart in Korçë allowed it to go ahead and was reprimanded). The Greek authorities even ignored offers of Albanian expatriates to enlist as volunteers against Italy. The Greek occupation regime followed the regulations of international law and the Albanian civil administration was left intact and continued to operate, including law courts. No atrocities were committed and the safes of the state bank were discovered unopened after the Greeks withdrew.


title: Greco-Italian War

text: Hitler blamed Mussolini's "Greek fiasco" for his failed campaign in Russia. "But for the difficulties created for us by the Italians and their idiotic campaign in Greece", he commented in mid-February 1945, "I should have attacked Russia a few weeks earlier," he later said. Hitler noted that, the "pointless campaign in Greece", Germany was not notified in advance of the impending attack, which "compelled us, contrary to all our plans, to intervene in the Balkans, and that in its turn led to a catastrophic delay in the launching of our attack on Russia. We were compelled to expend some of our best divisions there. And as a net result we were then forced to occupy vast territories in which, but for this stupid show, the presence of our troops would have been quite unnecessary". "We have no luck with the Latin races", he complained afterwards. Mussolini took advantage of Hitler's preoccupation with Spain and France "to set in motion his disastrous campaign against Greece". Andreas Hillgruber has accused Hitler of trying to deflect blame for his country's defeat from himself to his ally, Italy.


title: Greco-Italian War

text: Ian Kershaw wrote that the five-week delay in launching Operation Barbarossa, caused by the unusually wet weather in May 1941, was not decisive. For Kershaw, the reasons for the ultimate failure of Barbarossa lay in the arrogance of the German war goals, in particular the planning flaws and resource limitations that caused problems for the operation from the start. He adds that the German invasion into Greece in spring 1941 did not cause significant damage to tanks and other vehicles needed for Barbarossa, the equipment diverted to Greece being used on the southern flank of the attack on the Soviet Union. Von Rintelen emphasizes that although the diversion of German resources into Greece just prior to the attack on the Soviet Union did little for the latter operation, Italy's invasion of Greece did not undermine Barbarossa before the operation started. Instead, Italy's invasion of Greece was to have serious consequences for its ongoing campaign in North Africa. Moreover, Italy would have been in a better position to execute its North African campaign had it initially occupied Tunis and Malta.


title: Greco-Italian War

text: In the preface to the collection of documents published in 1965 by the Italian Ministry of Foreign Affairs, the historian and diplomat Mario Toscano summed up the war as follows: "As we all know, the campaign against Greece ended in total failure. This was due, as the published material confirms, to Mussolini's conviction, based on indications he received from his colleagues, that the campaign would be decided in the political rather than the military sector. The consequences of this error were so serious as to bring about Italy's complete subjection to Germany as far as the political and military direction of the war was concerned." This has been echoed by other writers since: Gann and Duignan regarded that the fighting in France, Yugoslavia and Greece reduced Italy to the status of a [German] satellite, while Ian Kershaw considers that the Greek failure, the Battle of Taranto (11–12 November 1940) and the loss of Cyrenaica (9 December 1940 – 9 February 1941) served to end Italian aspirations to great power status.


title: Greco-Italian War

text: Other authors have been critical of the Italian leadership's handling of the operation. Jowett wrote in 2000 that Mussolini's "quick and relatively easy victory" turned to defeat and stalemate, which exposed the incompetence of the Fascist government and its war machine. Italian soldiers suffered great hardship in the Albanian mountains, "due to the incompetence and unforgivably bad planning of their leaders". In 2008, Paoletti wrote that the Italian army fought in difficult terrain, was short of clothing and equipment and units were split up as they arrived and used piecemeal. Mussolini was guilty of "criminal improvidence", in causing the great number casualties of the Italian army. The German invasion "went smoothly, because the Greek army was concentrated against the Italians". In 2009, Mazower wrote that the Italian invasion of Greece was a disaster and the "first Axis setback" of the war. Mussolini had sent troops to attack Greece, over some of the worst mountain country in Europe, at the beginning of winter. The Greeks repulsed the invasion, to the surprise of enemies and Allies alike, an event made worse for the Fascist regime because of the attack on Taranto and the disasters in Libya, Eritrea and Ethiopia.


title: Greco-Italian War

text: Several military historians have blamed the poor performance of the Italian Army in Greece, as well as in France and North Africa, on "innate defects" that had been evident already during World War I but were consistently ignored due to institutional indifference. The Italian military historian Lucio Ceva remarks that the Italian military was largely unable to learn from its failures or from the enemies it faced; as military historian Brian R. Sullivan points out, it took several decades before the historical office of the Italian General Staff published studies on Italian reverses like Caporetto or Guadalajara. Sullivan also demonstrates that the deficiencies in doctrine, training, leadership, organization and logistics that were apparent during the Spanish Civil War were simply ignored. A typical example is the testing in Spain of the new binary divisions; although they proved "too weak against opponents better armed than the Ethiopians and [...] too inflexible in maneuver", so that the Italian divisions in Spain reverted to the traditional triangular pattern in November 1937, in the very same month, Army chief of staff Pariani insisted on pressing on with the reorganization as the greater number of divisions resulting from it "would give Fascist Italy the appearance of greater military power". The diversion of large quantities of material and funds to the Spanish intervention also impacted the Italian Army negatively: according to the official Italian history of the conflict, the material left in or donated to Spain would have sufficed to provide for 55 fully equipped divisions in June 1940, rather than the 19 fully and 34 partially equipped ones in reality.


title: Greco-Italian War

text: According to James Sadkovich, the effect of the Italo-Greek war has been exaggerated by other authors, because Axis victories in the spring of 1941 cancelled the Italian defeats of the previous winter. However, even he admits the adverse effect that the start of the Greek campaign had on Italy's war already under way in North Africa. Between October 1940 and May 1941, five times as many men, one and a third times as much "matériel", three and a half times more merchant ships and at least twice the amount of escort vessels were deployed on the Greek operation as in North Africa. As a result, the initial numerical superiority that the Italians enjoyed over the British in the region, was not to last. Graziani deferred his advance, aware that Italian strength was insufficient to mount the major offensive through Egypt that Mussolini was urging and expecting. The Germans saw the importance of the sector and offered troops and equipment. The "Comando Supremo" wanted to take advantage of the offer. It could have made the difference but Mussolini refused.


title: Greco-Italian War

text: Anti-Italian feeling among the Greek public, already strong, reached its peak after the sinking of "Elli" on 15 August 1940, the day of the Dormition of the Mother of God, a major Orthodox religious holiday. Greek optimism that the Italian attack would fail was evident from the first moments of the war. Besides, official propaganda, as well as the spontaneous reaction of the people created the optimism which was necessary for the first difficult moments. From the first hours of the war a strong national feeling was quite evident "to teach a lesson to the macaroni-boys" (, ""Makaronades""), as the Italians were pejoratively called. Various factors have contributed to the high morale of the Greek side and the subsequent repulsion of the Italian attacks: the strong belief in a just cause, the specialized and well trained military personnel of the Greek army and its leadership, as well as the devotion of the civilian population who lived next to the battlefields, including women, children and the elderly, to the Greek cause. Public opinion in Greece still accepts that the failure of the numerically superior Italian army came as a result of its unjustified action against Greece.


title: Greco-Italian War

text: After the Italian troops were driven from Greek soil, Greek morale was further strengthened. The unpublished and unknown up to now documents (memoranda, letters, plans) of Ubaldo Soddu (who did not write memoirs), Commander of the Italian forces in Albania from 10 November to 30 December 1940, reveal the desperate efforts for control, the strict measures for unjustified retreats and abandonment of positions, the tragic appeal even for German help (on 24 November and 17 December). In his reports, Soddu analysed Greek offensive tactics and the bravery and the moral strength of the enemy, during this period from November–December, the Greeks used no new method of military tactics or quickly took advantage of the land left back by the Italian retreat. Mussolini, after the capture of Himara by the Greeks, wrote of the high morale that contributed to the victory of the enemy (24 December). The Greek successes against Italy helped raise morale in Allied Europe and showed that the Axis were not invincible. Inspired by these military developments, British Prime Minister, Winston Churchill, declared that "today we say that Greeks fight like heroes, from now on we will say that heroes fight like Greeks".


title: Greco-Italian War

text: In 2007, Fisher wrote that although the advance of the Greek army stalled at January 1941, due to harsh winter conditions and Italian reinforcements, Greece had managed to secure a strong bridgehead in southern Albania (Northern Epirus to the Greeks). Thus, it not only delivered a humiliation to Mussolini, but also occupied an area inhabited by a substantial ethnic Greek population,


title: Greco-Italian War

text: The Greco-Italian War is viewed as a triumph in Greece and often referred to as "the Epic of 40" ("Το Έπος του '40") and 28 October, the day Metaxas rejected the Italian ultimatum, is a national holiday known as Ohi Day (, ""Anniversary of the 'No"'").


title: Greco-Italian War

text: The difficulty Italy encountered in subduing a minor power such as Greece further lowered the opinion among the Germans of their Italian allies. German SS-"Oberst-Gruppenführer" Sepp Dietrich labeled the Albania campaign as one of the three "great disasters [that have] deprived the Italian Army of its former confidence", along with the Italian invasion of France and Operation Compass. He bitterly noted: "For this attack they used troops from Southern Italy- exactly what was needed for a winter campaign in mountainous country, without proper equipment, over an impracticable terrain, and without any organization in depth!". Wilhelm Keitel, commenting about the end of the campaign, said that "this miserable spectacle, laid on by our gallant ally, must have produced some hollow laughter from the Greeks."


title: Greco-Italian War

text: Others among the German leadership were less critical, most notably Adolf Hitler. In his address to the Reichstag following the conclusion of the Balkan Campaign, Hitler was complimentary to the Greeks for their "extremely brave resistance", but stated that given the Greek logistical situation, German involvement was not decisive in the Greco-Italian conflict: "The Duce... was convinced that a quick decision would be arrived at one way or another in the forthcoming season. I was of the same opinion." He stated that he had no quarrel with Greece (which he had acknowledged as part of the Italian sphere anyway) and that his intervention was aimed solely at the British as he suspected that they planned to set up a threat to his rear in the vein of the Salonika front of the First World War: "the German forces, therefore, represented no assistance to Italy against Greece, but a preventive measure against the British." He further noted that by the beginning of April the Albanian campaign against the Italians "had so weakened [Greece] that its collapse had already become inevitable", and credited the Italians with having "engaged the greater part of the Greek Army." In his private correspondence in April 1942, Hitler said: "It is equally impossible to imagine what might have happened if the Italian front had not been stabilized in Albania, thanks to Mussolini; the whole of the Balkans would have been set alight at a moment when our advance towards the southeast was still in its early stages."


title: Greco-Italian War

text: The Italian invasion began with a force of about and was increased to about supported by and Italian forces suffered casualties of and (of whom taken prisoner), for a total of in action and cases for a grand total of Eighteen ships of the "Regia Marina" were sunk. The "Regia Aeronautica" had 79 aircraft destroyed (65 shot down) and more than 400 damaged, with killed, while claiming 218 kills against Greek and British and 55 probables. Greek military forces amounted to fewer than with casualties of and for a total of and frostbite cases, a grand total of about The RHAF lost between aircraft. (In Operation Marita, the Germans took and prisoners.)


title: Greco-Italian War

text: In January 2018, following an agreement between the Greek and Albanian foreign ministers, a systematic effort to recover the bodies of fallen Greek soldiers from the war was undertaken between Greece and Albania. It is estimated that between 6,800 and 8,000 fallen Greek soldiers were hastily buried on location following their death, and their remains not properly identified. Work by joint Greek-Albanian teams began on 22 January in the Kelcyre Gorge, site of the Battle of Kleisoura Pass. A small number of Cham Albanian activists tried to disrupt the work but were removed by Albanian police. The remains of the Greek soldiers will be buried in the Greek military cemeteries in the Kelcyre Gorge and in the Greek minority village of Bularat (Vouliarates) near the Greek-Albanian border.


title: Greco-Italian War

text: On 13 April, Hitler issued Directive 27, including his occupation policy for Greece and jurisdiction in the Balkans with Directive No. 31 (9 June). Italy occupied the bulk of the mainland, German forces occupied Athens, Thessaloniki, Central Macedonia and several Aegean islands, including most of Crete and Florina, subject of disputed claims by Italy and Bulgaria. Bulgaria, which had not participated in the invasion, occupied most of Thrace on the same day that Tsolakoglou surrendered taking the territory between the Strymon river and a line through Alexandroupoli and Svilengrad west of the Evros River. Italian troops took over their zone of occupation from 28 April to 12 June.


title: In Another World with My Smartphone

text: Fifteen-year-old Touya Mochizuki is accidentally killed by God. As an apology, God allows him to be resurrected, but since he cannot send him back to his old world, he instead reincarnates him into a fantasy world along with any special requests. Touya requested to bring his smartphone into the new world with him, which God modifies. As such, while Touya cannot contact his old world with it, the phone can be easily recharged by magic and can otherwise function such as accessing data from the old world and can use relevant features for his new world such as the GPS function to locations which are comprehensively identified on it.


title: In Another World with My Smartphone

text: God also greatly amplifies Touya's physical, magical, and cognitive abilities to a certain degree as a further apology for the inconvenience of killing him. Taking full advantage of his second chance at life, Touya befriends many different people, mainly women and high-ranking people in the new world. He begins to travel from country to country, solving political disputes, minor quests, and nonchalantly enjoying himself with his newfound allies.


title: In Another World with My Smartphone

text: The series began publication as a web novel, being serialized on the Shōsetsuka ni Narō website since April 8, 2013. The series was later published as a light novel series by Hobby Japan's "HJ Novels" label beginning on May 22, 2015; twenty-seven volumes have been published as of October 19, 2022. The light novel features illustrations by Eiji Usatsuka. It was licensed for digital distribution in the English language by J-Novel Club. J-Novel Club announced at Anime Expo on July 5, 2018 that the series would be the first it would publish in print outside its deal with Seven Seas Entertainment. The novels is published in a partnership with Ingram Publisher Services.


title: In Another World with My Smartphone

text: A manga adaptation by Soto began serialization in the January 2017 issue of Comp Ace (published November 2016), with the first two compiled tankōbon volumes released consecutively in June and July 2017 and the third volume in February 2018. Yen Press announced during its panel at the New York Comic Con Metaverse digital event in October 2020 that it had licensed the manga.


title: In Another World with My Smartphone

text: An anime television series adaptation directed by Takeyuki Yanase, written by Natsuko Takahashi, and animated by Production Reed was announced and aired from July 11 to September 26, 2017. AŌP performed the opening theme song "Another World" while Maaya Uchida, Yui Fukuo, Chinatsu Akatsuki, Marika Kouno, Nanami Yamashita, and Sumire Uesaka. performed different versions of the ending theme song . Crunchyroll streamed and licensed the series, while Funimation produced an English dub and released it on home video as part of the two companies' partnership. Funimation released the series for home video in the British Isles, and in Australia and New Zealand, through their distributors at Sony Pictures UK and Universal Sony respectively.


title: In Another World with My Smartphone

text: A second season was announced on April 15, 2022. The second season will be animated by J.C.Staff and directed by Yoshiaki Iwasaki, with Deko Akao handling series composition, Chinatsu Kameyama designing the characters and serving as chief animation director, and Kei Yoshikawa and Kōhei Yamada composing the music. The cast will reprise their roles from the first season and the drama CD. It will premiere in April 2023.


title: In Another World with My Smartphone

text: The series has seen considerable popularity on the Shōsetsuka ni Narō website, having been viewed over 100,000,000 times in total.


title: Kira Buckland

text: Kira Buckland (born July 16, 1987) is an American voice actress, who has provided voices for English dubbed Japanese anime, cartoons, and video games. Some of her major roles are Jolyne Cujoh in "," in "," Reimi Sugimoto in "", Trucy Wright in the "Ace Attorney" series, Hiyoko Saionji and Kirumi Tojo in the "Danganronpa" series, Rebecca Bluegarden in "Edens Zero," Celine and Elise Schwarzer in "" series, Talim in "Soulcalibur VI" (including 2B as its guest character), Beatrice in "", Heart Aino from "Arcana Heart" series in "", Mitsuri Kanroji in "", Falke in "Street Fighter V", Edna in "Tales of Zestiria", Mary Saotome in "Kakegurui", Yung in "Godzilla Singular Point", Julis-Alexia von Riessfeld in "The Asterisk War," and Kuki Shinobu in "Genshin Impact".


title: Kira Buckland

text: Buckland started voice acting in 2004, where she worked on radio dramas, Newgrounds flash animations, and computer/video games. While a student at West High School, she became president of the anime club and founded the first Alaskan anime convention with the president of the anime club from Dimond High, Senshi-Con, based in Anchorage, Alaska. She won the Anime Expo 2007 Idol Voice Acting competition, as well as the Sakura-Con 2007 animated voice acting award. She is primarily known for her voice work on video games and anime shows.


title: Kira Buckland

text: Buckland graduated with a degree in Japanese and is proficient in Spanish. She moved to Southern California in 2011 and worked miscellaneous jobs while training to be a professional voice actor, such as a feline neonatal caregiver.


title: Kira Buckland

text: Before her professional career, Buckland was familiar with the manga series "JoJo's Bizarre Adventure", got a tattoo of a star on the back of her neck which resembles the Joestar Birthmark, and during her career expressed a desire to voice of the character Jolyne Cujoh in an official project, which she accomplished with the release of "".


title: Bayesian network

text: A Bayesian network (also known as a Bayes network, Bayes net, belief network, or decision network) is a probabilistic graphical model that represents a set of variables and their conditional dependencies via a directed acyclic graph (DAG). Bayesian networks are ideal for taking an event that occurred and predicting the likelihood that any one of several possible known causes was the contributing factor. For example, a Bayesian network could represent the probabilistic relationships between diseases and symptoms. Given symptoms, the network can be used to compute the probabilities of the presence of various diseases.


title: Bayesian network

text: Efficient algorithms can perform inference and learning in Bayesian networks. Bayesian networks that model sequences of variables ("e.g." speech signals or protein sequences) are called dynamic Bayesian networks. Generalizations of Bayesian networks that can represent and solve decision problems under uncertainty are called influence diagrams.


title: Bayesian network

text: Formally, Bayesian networks are directed acyclic graphs (DAGs) whose nodes represent variables in the Bayesian sense: they may be observable quantities, latent variables, unknown parameters or hypotheses. Edges represent conditional dependencies; nodes that are not connected (no path connects one node to another) represent variables that are conditionally independent of each other. Each node is associated with a probability function that takes, as input, a particular set of values for the node's parent variables, and gives (as output) the probability (or probability distribution, if applicable) of the variable represented by the node. For example, if formula_1 parent nodes represent formula_1 Boolean variables, then the probability function could be represented by a table of entries, one entry for each of the possible parent combinations. Similar ideas may be applied to undirected, and possibly cyclic, graphs such as Markov networks.


title: Bayesian network

text: Two events can cause grass to be wet: an active sprinkler or rain. Rain has a direct effect on the use of the sprinkler (namely that when it rains, the sprinkler usually is not active). This situation can be modeled with a Bayesian network (shown to the right). Each variable has two possible values, T (for true) and F (for false).


title: Bayesian network

text: where "G" = "Grass wet (true/false)", "S" = "Sprinkler turned on (true/false)", and "R" = "Raining (true/false)".


title: Bayesian network

text: The model can answer questions about the presence of a cause given the presence of an effect (so-called inverse probability) like "What is the probability that it is raining, given the grass is wet?" by using the conditional probability formula and summing over all nuisance variables:


title: Bayesian network

text: Using the expansion for the joint probability function formula_5 and the conditional probabilities from the conditional probability tables (CPTs) stated in the diagram, one can evaluate each term in the sums in the numerator and denominator. For example,


title: Bayesian network

text: To answer an interventional question, such as "What is the probability that it would rain, given that we wet the grass?" the answer is governed by the post-intervention joint distribution function


title: Bayesian network

text: obtained by removing the factor formula_9 from the pre-intervention distribution. The do operator forces the value of G to be true. The probability of rain is unaffected by the action:


title: Bayesian network

text: These predictions may not be feasible given unobserved variables, as in most policy evaluation problems. The effect of the action formula_13 can still be predicted, however, whenever the back-door criterion is satisfied. It states that, if a set "Z" of nodes can be observed that "d"-separates (or blocks) all back-door paths from "X" to "Y" then


title: Bayesian network

text: A back-door path is one that ends with an arrow into "X". Sets that satisfy the back-door criterion are called "sufficient" or "admissible." For example, the set "Z" = "R" is admissible for predicting the effect of "S" = "T" on "G", because "R" "d"-separates the (only) back-door path "S" ← "R" → "G". However, if "S" is not observed, no other set "d"-separates this path and the effect of turning the sprinkler on ("S" = "T") on the grass ("G") cannot be predicted from passive observations. In that case "P"("G" | do("S" = "T")) is not "identified". This reflects the fact that, lacking interventional data, the observed dependence between "S" and "G" is due to a causal connection or is spurious


title: Bayesian network

text: To determine whether a causal relation is identified from an arbitrary Bayesian network with unobserved variables, one can use the three rules of ""do"-calculus" and test whether all "do" terms can be removed from the expression of that relation, thus confirming that the desired quantity is estimable from frequency data.


title: Bayesian network

text: Using a Bayesian network can save considerable amounts of memory over exhaustive probability tables, if the dependencies in the joint distribution are sparse. For example, a naive way of storing the conditional probabilities of 10 two-valued variables as a table requires storage space for formula_15 values. If no variable's local distribution depends on more than three parent variables, the Bayesian network representation stores at most formula_16 values.


title: Bayesian network

text: One advantage of Bayesian networks is that it is intuitively easier for a human to understand (a sparse set of) direct dependencies and local distributions than complete joint distributions.


title: Bayesian network

text: Because a Bayesian network is a complete model for its variables and their relationships, it can be used to answer probabilistic queries about them. For example, the network can be used to update knowledge of the state of a subset of variables when other variables (the "evidence" variables) are observed. This process of computing the "posterior" distribution of variables given evidence is called probabilistic inference. The posterior gives a universal sufficient statistic for detection applications, when choosing values for the variable subset that minimize some expected loss function, for instance the probability of decision error. A Bayesian network can thus be considered a mechanism for automatically applying Bayes' theorem to complex problems.


title: Bayesian network

text: The most common exact inference methods are: variable elimination, which eliminates (by integration or summation) the non-observed non-query variables one by one by distributing the sum over the product; clique tree propagation, which caches the computation so that many variables can be queried at one time and new evidence can be propagated quickly; and recursive conditioning and AND/OR search, which allow for a space–time tradeoff and match the efficiency of variable elimination when enough space is used. All of these methods have complexity that is exponential in the network's treewidth. The most common approximate inference algorithms are importance sampling, stochastic MCMC simulation, mini-bucket elimination, loopy belief propagation, generalized belief propagation and variational methods.


title: Bayesian network

text: In order to fully specify the Bayesian network and thus fully represent the joint probability distribution, it is necessary to specify for each node "X" the probability distribution for "X" conditional upon "X"'s parents. The distribution of "X" conditional upon its parents may have any form. It is common to work with discrete or Gaussian distributions since that simplifies calculations. Sometimes only constraints on distribution are known; one can then use the principle of maximum entropy to determine a single distribution, the one with the greatest entropy given the constraints. (Analogously, in the specific context of a dynamic Bayesian network, the conditional distribution for the hidden state's temporal evolution is commonly specified to maximize the entropy rate of the implied stochastic process.)


title: Bayesian network

text: Often these conditional distributions include parameters that are unknown and must be estimated from data, e.g., via the maximum likelihood approach. Direct maximization of the likelihood (or of the posterior probability) is often complex given unobserved variables. A classical approach to this problem is the expectation-maximization algorithm, which alternates computing expected values of the unobserved variables conditional on observed data, with maximizing the complete likelihood (or posterior) assuming that previously computed expected values are correct. Under mild regularity conditions, this process converges on maximum likelihood (or maximum posterior) values for parameters.


title: Bayesian network

text: A more fully Bayesian approach to parameters is to treat them as additional unobserved variables and to compute a full posterior distribution over all nodes conditional upon observed data, then to integrate out the parameters. This approach can be expensive and lead to large dimension models, making classical parameter-setting approaches more tractable.


title: Bayesian network

text: In the simplest case, a Bayesian network is specified by an expert and is then used to perform inference. In other applications, the task of defining the network is too complex for humans. In this case, the network structure and the parameters of the local distributions must be learned from data.


title: Bayesian network

text: Automatically learning the graph structure of a Bayesian network (BN) is a challenge pursued within machine learning. The basic idea goes back to a recovery algorithm developed by Rebane and Pearl and rests on the distinction between the three possible patterns allowed in a 3-node DAG:


title: Bayesian network

text: The first 2 represent the same dependencies (formula_17 and formula_18 are independent given formula_19) and are, therefore, indistinguishable. The collider, however, can be uniquely identified, since formula_17 and formula_18 are marginally independent and all other pairs are dependent. Thus, while the "skeletons" (the graphs stripped of arrows) of these three triplets are identical, the directionality of the arrows is partially identifiable. The same distinction applies when formula_17 and formula_18 have common parents, except that one must first condition on those parents. Algorithms have been developed to systematically determine the skeleton of the underlying graph and, then, orient all arrows whose directionality is dictated by the conditional independences observed.


title: Bayesian network

text: An alternative method of structural learning uses optimization-based search. It requires a scoring function and a search strategy. A common scoring function is posterior probability of the structure given the training data, like the BIC or the BDeu. The time requirement of an exhaustive search returning a structure that maximizes the score is superexponential in the number of variables. A local search strategy makes incremental changes aimed at improving the score of the structure. A global search algorithm like Markov chain Monte Carlo can avoid getting trapped in local minima. Friedman et al. discuss using mutual information between variables and finding a structure that maximizes this. They do this by restricting the parent candidate set to "k" nodes and exhaustively searching therein.


title: Bayesian network

text: A particularly fast method for exact BN learning is to cast the problem as an optimization problem, and solve it using integer programming. Acyclicity constraints are added to the integer program (IP) during solving in the form of cutting planes. Such method can handle problems with up to 100 variables.


title: Bayesian network

text: In order to deal with problems with thousands of variables, a different approach is necessary. One is to first sample one ordering, and then find the optimal BN structure with respect to that ordering. This implies working on the search space of the possible orderings, which is convenient as it is smaller than the space of network structures. Multiple orderings are then sampled and evaluated. This method has been proven to be the best available in literature when the number of variables is huge.


title: Bayesian network

text: Another method consists of focusing on the sub-class of decomposable models, for which the MLE have a closed form. It is then possible to discover a consistent structure for hundreds of variables.


title: Bayesian network

text: Learning Bayesian networks with bounded treewidth is necessary to allow exact, tractable inference, since the worst-case inference complexity is exponential in the treewidth k (under the exponential time hypothesis). Yet, as a global property of the graph, it considerably increases the difficulty of the learning process. In this context it is possible to use K-tree for effective learning.


title: Bayesian network

text: Given data formula_24 and parameter formula_25, a simple Bayesian analysis starts with a prior probability ("prior") formula_26 and likelihood formula_27 to compute a posterior probability formula_28.


title: Bayesian network

text: Often the prior on formula_25 depends in turn on other parameters formula_30 that are not mentioned in the likelihood. So, the prior formula_26 must be replaced by a likelihood formula_32, and a prior formula_33 on the newly introduced parameters formula_30 is required, resulting in a posterior probability


title: Bayesian network

text: The process may be repeated; for example, the parameters formula_30 may depend in turn on additional parameters formula_37, which require their own prior. Eventually the process must terminate, with priors that do not depend on unmentioned parameters.


title: Bayesian network

text: Given the measured quantities formula_38each with normally distributed errors of known standard deviation formula_39,


title: Bayesian network

text: Suppose we are interested in estimating the formula_41. An approach would be to estimate the formula_41 using a maximum likelihood approach; since the observations are independent, the likelihood factorizes and the maximum likelihood estimate is simply


title: Bayesian network

text: However, if the quantities are related, so that for example the individual formula_41have themselves been drawn from an underlying distribution, then this relationship destroys the independence and suggests a more complex model, e.g.,


title: Bayesian network

text: with improper priors formula_47, formula_48. When formula_49, this is an "identified model" (i.e. there exists a unique solution for the model's parameters), and the posterior distributions of the individual formula_41 will tend to move, or "shrink" away from the maximum likelihood estimates towards their common mean. This "shrinkage" is a typical behavior in hierarchical Bayes models.


title: Bayesian network

text: Some care is needed when choosing priors in a hierarchical model, particularly on scale variables at higher levels of the hierarchy such as the variable formula_51 in the example. The usual priors such as the Jeffreys prior often do not work, because the posterior distribution will not be normalizable and estimates made by minimizing the expected loss will be inadmissible.


title: Bayesian network

text: Several equivalent definitions of a Bayesian network have been offered. For the following, let "G" = ("V","E") be a directed acyclic graph (DAG) and let "X" = ("X"), "v" ∈ "V" be a set of random variables indexed by "V".


title: Bayesian network

text: "X" is a Bayesian network with respect to "G" if its joint probability density function (with respect to a product measure) can be written as a product of the individual density functions, conditional on their parent variables:


title: Bayesian network

text: where pa("v") is the set of parents of "v" (i.e. those vertices pointing directly to "v" via a single edge).


title: Bayesian network

text: For any set of random variables, the probability of any member of a joint distribution can be calculated from conditional probabilities using the chain rule (given a topological ordering of "X") as follows:


title: Bayesian network

text: The difference between the two expressions is the conditional independence of the variables from any of their non-descendants, given the values of their parent variables.


title: Bayesian network

text: "X" is a Bayesian network with respect to "G" if it satisfies the "local Markov property": each variable is conditionally independent of its non-descendants given its parent variables:


title: Bayesian network

text: Developing a Bayesian network often begins with creating a DAG "G" such that "X" satisfies the local Markov property with respect to "G". Sometimes this is a causal DAG. The conditional probability distributions of each variable given its parents in "G" are assessed. In many cases, in particular in the case where the variables are discrete, if the joint distribution of "X" is the product of these conditional distributions, then "X" is a Bayesian network with respect to "G".


title: Bayesian network

text: The Markov blanket of a node is the set of nodes consisting of its parents, its children, and any other parents of its children. The Markov blanket renders the node independent of the rest of the network; the joint distribution of the variables in the Markov blanket of a node is sufficient knowledge for calculating the distribution of the node. "X" is a Bayesian network with respect to "G" if every node is conditionally independent of all other nodes in the network, given its Markov blanket.


title: Bayesian network

text: This definition can be made more general by defining the "d"-separation of two nodes, where d stands for directional. We first define the "d"-separation of a trail and then we will define the "d"-separation of two nodes in terms of that.


title: Bayesian network

text: Let "P" be a trail from node "u" to "v". A trail is a loop-free, undirected (i.e. all edge directions are ignored) path between two nodes. Then "P" is said to be "d"-separated by a set of nodes "Z" if any of the following conditions holds:


title: Bayesian network

text: The nodes "u" and "v" are "d"-separated by "Z" if all trails between them are "d"-separated. If "u" and "v" are not d-separated, they are d-connected.


title: Bayesian network

text: where "Z" is a set which "d"-separates "u" and "v". (The Markov blanket is the minimal set of nodes which "d"-separates node "v" from all other nodes.)