Greece in the Balkan Wars The participation of Greece in the Balkan Wars of 1912 – 1913 is one of the most important episodes in modern Greek history , as it allowed the Greek state to almost double its size and achieve most of its present territorial size . It also served as a catalyst of political developments , as it brought to prominence two personalities , whose relationship would dominate the next decade and have long - lasting repercussions for Greece : the Prime Minister Eleftherios Venizelos , and the Army ' s commander - in - chief , the Crown Prince and later King , Constantine I . In the First Balkan War , Greece was allied with Bulgaria , Serbia and Montenegro in the " Balkan League " against the Ottoman Empire . The war began on with the declaration of war by Montenegro , while Greece , Bulgaria and Serbia joined on . During this war , Greece fought on two fronts on land , and also shouldered the main naval effort of the Balkan allies . The initial principal thrust on land was by the Army of Thessaly , which succeeded in occupying much of Macedonia , including the strategically important port of Thessaloniki , the latter just hours ahead of a Bulgarian division ; this would result in increased tension between the two allies in the coming months , and would be one of the causes of the Second Balkan War . Following the successful conclusion of operations in Macedonia , the Greek Army shifted its weight to the Epirus front , where , after a prolonged siege , the city of Ioannina fell , and the Greeks advanced into " Northern Epirus " ( modern southern Albania ) . In the Aegean Sea , the Greek Navy took possession of all the Aegean islands except for the Italian - occupied Dodecanese , and fought off two attempts by the Ottoman Navy to sally forth from the Dardanelles . Although negotiations had started in London in December 1912 , the war continued until , when the Treaty of London was finally signed . The treaty failed to satisfy any party involved , with the chief point of friction being the partition of Macedonia . In the face of Bulgarian claims , Serbia and Greece formed an alliance , and on the evening of , Bulgarian forces launched a surprise attack against their erstwhile allies . The Bulgarian attacks were soon contained , and pushed back . For Greece in particular , the battles of the Second Balkan War were very costly , as the Greek Army pushed its way into Bulgaria . Following the entry of Romania and the Ottoman Empire in the war , the Bulgarian position became hopeless , and an armistice was declared on 30 July . The war was concluded with the Treaty of Bucharest on 10 August 1913 , which confirmed the Greek gains of Macedonia , Epirus ( without Northern Epirus ) and Crete . Background . The rise of Balkan nationalism . The Balkan Wars must be regarded within the context of the rising Balkan nationalisms during the 19th century , which ran counter to the established Ottoman religion - based " millet " system . Inspired by the theories of nationalism as expounded in contemporary France , Germany and Italy , Balkan intellectual elites sought to awaken the national consciousness of their compatriots and advocated the creation of ethnically homogeneous nation - state s . The first states to be formed out of the Ottoman Empire were Serbia ( as an autonomous principality in 1804 – 1817 ) and Greece ( as a fully independent kingdom in 1821 – 1832 ) , in both cases following protracted wars . In both cases also , the new states formed only a fraction of the lands claimed as belonging to the respective nations . In the Greek case , fully three quarters of all Greeks still lived under Ottoman rule , and the drive to liberate their " unredeemed " brethren became known as the " Megali Idea " , first articulated by the Greek Prime Minister Ioannis Kolettis before Parliament in 1844 : Kolettis thus united the nascent Greek state , which initially had hearkened back mostly to the glories of Classical Greece , with the vision of a restored Byzantine Empire . The process of restoring the Byzantine Empire as an integral part of Greek national consciousness , and consequently claiming its cultural and territorial heritage , was carried out by Greece ' s " national historian " , Constantine Paparrigopoulos . Likewise , Serbia sought to revive the empire of Stefan Dusan , and the latecomers in the Balkan nation - building , the Bulgarians , the medieval Bulgarian Empires . Following the Treaty of San Stefano in 1877 , this " greater Bulgaria " seemed to be realized , but was reduced drastically in the subsequent Treaty of Berlin , which also ceded Thessaly to Greece . This episode however made clear that the Balkan nationalisms were mutually competitive , and nowhere was this competition clearer than in the great region that lay between the three states , Macedonia . Macedonia . Macedonia was inhabited by a dense mixture of nationalities , including Greeks , Bulgarians , Serbs , Vlachs , Turks and other Balkan Muslims , Albanians , and featured even a large community of Sephardic Jews , who were the dominant element in the region ' s major city , Thessaloniki . All countries with minorities in the region tried to make progress at the expense of the others , funding schools and publishing ethnographic statistics and maps that supported their claims . In the late 1890s , the antagonism for Macedonia , hitherto mostly confined to a cultural and propaganda war , entered a new phase , as the pro - Bulgarian Internal Macedonian Revolutionary Organization , founded in 1893 , initiated an armed guerrilla campaign against the Ottomans . Following the Ilinden Uprising , the Bulgarian efforts were countered by Serb and Greek armed groups , in what is known as the " Macedonian Struggle " in Greece . These armed bands functioned as the military wing of national committees that carried out an intensive campaign of cultural assimilation amongst the rural populace , funding schools and orphanages , among other things . Sporadic fighting took place between Bulgarian " komitadji s " , Greek " andartes " and Ottoman gendarmes . Looting , arson and assassinations were commonplace , as each side sought to intimidate the other ' s supporters . The clashes ended only with the outbreak of the Young Turk Revolution in 1908 , which promised equality to all Ottoman subjects . Ottoman weakness . The Young Turk Revolution ushered a period of instability in the region . Seizing the opportunity , Bulgaria unilaterally declared its full independence , Austria - Hungary annexed Bosnia and Herzegovina , angering the Serbs and Russians , while Crete also declared its union ( " enosis " ) with Greece , although the latter was not formalized . Initially , the liberal promises of the Young Turks caused much enthusiasm both inside the Empire and in the Balkan states , but they gradually adopted a policy of forced " Ottomanisation " , which , coupled with the parallel rise of Albanian nationalism , threatened the interests of the other Balkan states . Italy too , in search of a colonial empire , took advantage of the turmoil in the Ottoman Empire , attacking Libya and seizing the Dodecanese islands during the Italo - Turkish War . The Italians promised to cede the Greek - inhabited Dodecanese islands to Greece , but in the end kept them . This aroused indignation in Greece . Coupled with Bulgarian aspirations for Macedonia and Austrian designs on Thessaloniki , it made clear that , if Greece did not want to be left out of the Ottoman spoils , it had to act . Nevertheless , the new Greek Prime Minister , Eleftherios Venizelos , hesitated to act alone , not only because of the bitter memories of the disastrous war of 1897 , but also because the large Greek populations inside Ottoman territory might be exposed to reprisals . Creation of the Balkan League . Spurred by the Ottomans ' entanglement with Italy , Serbia and Bulgaria accelerated their negotiations for an alliance ; however , their differences proved difficult to overcome , and only pressure from the Russian government , which was eager to regain ground in the Balkans , led to the signing of a treaty of alliance on . It was ostensibly directed against Austria - Hungary , but it also envisaged a partition of European Turkey : Albania and Kosovo to Serbia , Thrace to Bulgaria ; southern Macedonia would be received by Bulgaria , while its northern part would be partitioned between the two under the arbitration of the Russian Tsar . Feelers about a rapprochement and an alliance had also been put forward to Bulgaria by Venizelos in early 1911 , but not until after the conclusion of the Serbian - Bulgarian pact did negotiations commence in earnest . Bulgaria , the " Prussia of the Balkans " , had the region ' s strongest army , and in light of the 1897 debacle , the Greek army was held in low esteem . But Greece could offer its navy , which alone could prevent Ottoman reinforcements from being transported from Asia directly to the European fronts . As the Greek ambassador to Sofia noted : " Greece can provide 600 , 000 men for the war effort . 200 , 000 men in the field , and the fleet will be able to stop 400 , 000 men being landed by Turkey between Salonica and Gallipoli . " A treaty of defensive alliance was thus signed at Sofia on . Unlike the treaty with Serbia , no provisions were made for the division of territory , primarily because the Bulgarians assumed that their army would seize most of its aims before the Greeks got there . First Balkan War . Opposing forces . The various Balkan armies shared many similarities : they were organized along Western European lines , with a General Staff ( except for Montenegro ) staffed by officers educated abroad , a divisional structure , and were equipped with European arms , chiefly of French or German origin . Their backbone was the infantry , composed mostly of conscripted peasants , while their officers hailed chiefly from the middle classes . Among the Balkan nations , only Greece possessed a considerable navy , while Bulgaria was limited to a few torpedo boats to guard its Black Sea coast . Greece . Greece had a peacetime army of ca . 25 , 000 men , which , upon mobilization on grew to an overall strength of 110 , 000 men . This was divided into two major armies : the Army of Thessaly ( Στρατός Θεσσαλίας ) , commanded by the Crown Prince Constantine , which would strike in the direction of Macedonia , and the Army of Epirus ( Στρατός Ηπείρου ) under Lieutenant General Konstantinos Sapountzakis , which would strike in the direction of Epirus . The Army of Thessaly comprised seven infantry divisions , four independent " Evzones " battalions , a cavalry brigade and various support units , as well as four Farman aircraft , a total of 100 , 000 men , 70 machine guns and 120 artillery pieces , with 80 , 000 in the field . The Army of Epirus was of divisional strength , being composed of 8 infantry and one " Evzones " battalions , one cavalry company and 24 field guns , with a total of ca . 10 , 000 men . It was later reinforced by a Cretan volunteer regiment and by a corps of " Garibaldini " volunteers led by Giuseppe Garibaldi II , reaching some 13 , 000 men . Greek infantry divisions fielded three infantry regiments , one or two artillery battalions , and a cavalry - half - company for reconnaissance duties . Recently reorganized by a French military mission , the army was equipped with the Mannlicher - Schönauer rifle , and French artillery guns , chiefly the Canon de 75 modèle 1897 and the Schneider - Danglis mountain gun . Ottoman Empire . On the other side of the hill , the Ottomans , reorganized by a German military mission , had won a clear victory over Greece back in 1897 . Following the Young Turk Revolution however , the Ottoman army became involved in politics to the detriment of its efficiency .