Balkan Wars The Balkan Wars were two conflicts that took place in the Balkan Peninsula in south - eastern Europe in 1912 and 1913 . By the early 20th century , Bulgaria , Greece , Montenegro and Serbia had achieved independence from the Ottoman Empire , but large parts of their ethnic populations remained under Ottoman rule . In 1912 , these countries formed the Balkan League . There were three main causes of the First Balkan War . The Ottoman Empire was unable to reform itself , govern satisfactorily , or deal with the rising ethnic nationalism of its diverse peoples . Secondly the Great Powers quarrelled amongst themselves and failed to ensure that the Ottomans would carry out the needed reforms . This led the Balkan states to impose their own solution . Most important , the Balkan League had been formed , and its members were confident that it could defeat the Turks . Ottoman Empire lost almost all its European territories to the west of the River Maritsa , drawing present day Turkey ' s western border . Large influx of Turks started to flee into the Ottoman heartland as a result of the occupied lands by the allies . By 1914 , the remaining core region of the Ottoman Empire had experienced a population increase of around 2 . 5 million because of the flood of immigration from Balkans . In Turkey , it is considered a major disaster ( " Balkan harbi faciası " ) in the nation ' s history . The unexpected fall and sudden relinquishing of Turkish - dominated European territories created a psycho - traumatic event amongst the Turks that is said to have triggered the ultimate collapse of the empire itself within five years . Nazim Pasha , the chief of staff of the Ottoman army has been held responsible of the failure and was assassinated in 1913 by Young Turks . The First Balkan War broke out when the League attacked the Ottoman Empire on 8 October 1912 and was ended seven months later by the Treaty of London . After five centuries , the Ottoman Empire lost virtually all of its possessions in the Balkans . The Second Balkan War broke out on 16 June 1913 . Bulgaria was dissatisfied over the division of the spoils in Macedonia , made in secret by its former allies , Serbia and Greece , and attacked them . The Serbian and Greek armies repulsed the Bulgarian offensive and counter - attacked into Bulgaria , while Romania and the Ottoman Empire also attacked Bulgaria and gained ( or regained ) territory . In the resulting Treaty of Bucharest , Bulgaria lost most of the territories it had gained in the First Balkan War . Background . The background to the wars lies in the incomplete emergence of nation - states on the European territory of the Ottoman Empire during the second half of the 19th century . Serbia had gained substantial territory during the Russo - Turkish War , 1877 – 1878 , while Greece acquired Thessaly in 1881 ( although it lost a small area back to the Ottoman Empire in 1897 ) and Bulgaria ( an autonomous principality since 1878 ) incorporated the formerly distinct province of Eastern Rumelia ( 1885 ) . All three as well as Montenegro sought additional territories within the large Ottoman - ruled region known as Rumelia , comprising Eastern Rumelia , Albania , Macedonia , and Thrace ( " see map " ) . Policies of the Great Powers . Throughout the 19th century , the Great Power s shared different aims over the " Eastern Question " and the integrity of the Ottoman Empire . Russia wanted access to the " warm waters " of the Mediterranean ; it pursued a pan - Slavic foreign policy and therefore supported Bulgaria and Serbia . Britain wished to deny Russia access to the " warm waters " and supported the integrity of the Ottoman Empire , although it also supported a limited expansion of Greece as a backup plan in case integrity of the Empire was no longer possible . France wished to strengthen its position in the region , especially in the Levant ( today ' s Lebanon , Syria , the Palestinian territories and Israel ) . Habsburg - ruled Austria - Hungary wished for a continuation of the existence of the Ottoman Empire , since both were troubled multinational entities and thus the collapse of the one might weaken the other . The Habsburgs also saw a strong Ottoman presence in the area as a counterweight to the Serbian nationalistic call to their own Serb subjects in Bosnia . Italy , it has been argued , wished to recreate the Roman empire , though its primary aim at the time seems to have been the denial of access to the Adriatic Sea to another major sea power . The German Empire , in turn , under the " Drang nach Osten " policy , aspired to turn the Ottoman Empire into its own de facto colony , and thus supported its integrity . In the late 19th and early 20th century , Bulgaria and Greece contended for Ottoman Macedonia and Thrace . Ethnic Greeks sought the forced " Hellenization " of ethnic Bulgars , who sought " Bulgarization " of Greeks . Both nations sent armed irregulars into Ottoman territory to protect and assist their ethnic kindred . From 1904 , there was low intensity warfare in Macedonia between the Greek and Bulgarian bands and the Ottoman army ( the Struggle for Macedonia ) . After the Young Turk revolution of July 1908 , the situation changed drastically . Young Turk revolution . It is no surprise that the " Young Turk " revolution occurred in the troubled European provinces of the Empire . There the threat to its integrity was the most pronounced , and the need for reforms was most evident . When the revolt broke out , it was supported by intellectuals , the army , and almost all the ethnic minorities of the Empire , and forced Sultan Abdul Hamid II to re - adopt the long defunct Ottoman constitution of 1876 , ushering in the Second Constitutional Era . Hopes were raised among the Balkan ethnicities of reforms and autonomy , and elections were held to form a representative , multi - ethnic , Ottoman parliament . However , following the Sultan ' s attempted counter - coup , the liberal element of the Young Turks was sidelined and the nationalist element became dominant . At the same time , in October 1908 , Austria - Hungary seized the opportunity of the Ottoman political upheaval to annex the " de jure " Ottoman province of Bosnia and Herzegovina , which it had occupied since 1878 ( see " Bosnian Crisis " ) , and Bulgaria declared itself a fully independent kingdom . The Greeks of the autonomous Cretan State proclaimed unification with Greece , though the opposition of the Great Powers prevented the latter action from taking practical effect . Reaction in the Balkan States . Serbia was frustrated in the north by Austria - Hungary ' s incorporation of Bosnia . In March 1909 , Serbia was forced to accept the annexation and restrain anti - Habsburg agitation by Serbian nationalists . Instead , the Serbian government looked to formerly Serb territories in the south , notably " Old Serbia " ( the Sanjak of Novi Pazar and the province of Kosovo ) . On 15 August 1909 the Military League , a group of Greek officers , took action against the government to reform their country ' s national government and reorganize the army . The League found itself unable to create a new political system , until the league summoned the Cretan politician Eleutherios Venizelos to Athens as its political adviser . Venizelos persuaded the king to revise the constitution and asked the League to disband in favor of a National Assembly . In March 1910 the Military League dissolved itself . Bulgaria , which had secured Ottoman recognition of her independence in April 1909 and enjoyed the friendship of Russia , also looked to districts of Ottoman Thrace and Macedonia . In August 1910 Montenegro followed Bulgaria ' s precedent by becoming a kingdom . Balkan League . Following Italy ' s victory in the Italo - Turkish War of 1911 – 1912 the Young Turks fell from power after a coup . The Balkan countries saw this as an opportunity to attack the Ottoman Empire and fulfill their desires of expansion . With the initial encouragement of Russian agents , a series of agreements was concluded between Serbia and Bulgaria in March 1912 . Military victory against the Ottoman Empire would not be possible while it could bring reinforcements from Asia . The condition of the Ottoman railways of the time was primitive , so most reinforcement would have to come by sea through the Aegean Sea . Greece was the only Balkan country with a navy powerful enough to deny use of the Aegean to the Ottoman Empire , thus a treaty between Greece and Bulgaria became necessary ; it was signed in May 1912 . Montenegro concluded agreements between Serbia and Bulgaria later that year . Bulgaria signed treaties with Serbia to divide the territory of northern Macedonia , but refused any similar agreement with Greece . Bulgaria ' s policy was that the agreement would limit Serbia ' s access to Macedonia , while at the same time Bulgaria could take as much as its army could regardless of Greek wishes . Bulgaria thought it could occupy the larger part of Aegean Macedonia and the important port city of Salonika before the Greeks could get there . This alliance between Greece , Serbia , Bulgaria , and Montenegro became known as the Balkan League ; its existence was undesirable for all the Great Powers . The League was loose at best , though secret liaison officers were exchanged between the Greek and the Serbian army after the war began . Greece delayed the start of the war several times in the summer of 1912 , to better prepare her navy , but Montenegro declared war on 8 October ( 25 September O . S . ) . Following an ultimatum to the Ottoman Empire , the remaining members of the alliance entered the conflict on 17 October . First Balkan War . The three Slavic allies ( Bulgaria , Serbia and Montenegro ) had laid out extensive plans to coordinate their war efforts , in continuation of their secret prewar settlements and under close Russian supervision ( Greece was not included ) . Serbia and Montenegro would attack in the theater of Sandjak , Bulgarian and Serbia in Macedonia and Thrace . The Ottoman Empire ' s situation was difficult . Its population of about 26 million people provided a massive pool of manpower , but 3 / 4 of the population and nearly all of the Muslim component lived in the Asian part of the Empire . Reinforcements had to come from Asia mainly by sea , which depended on the result of battles between the Turkish and Greek navies in the Aegean . With the outbreak of the war , the Ottoman Empire activated three Army HQs : the Thracian HQ in Constantinople , the Western HQ in Salonika , and the Vardar HQ in Skopje , against the Bulgarians , the Greeks and the Serbians respectively . Most of their available forces were allocated to these fronts . Smaller independent units were allocated elsewhere , mostly around heavily fortified cities . Montenegro was the first that declared war on 8 October ( 25 September O . S . ) . Its main thrust was towards Shkodra , with secondary operations in the Novi Pazar area . The rest of the Allies , after giving a common ultimatum , declared war a week later . Bulgaria attacked towards Eastern Thrace , being stopped only at the outskirts of Constantinople at the Çatalca line and the isthmus of the Gallipoli peninsula , while secondary forces captured Western Thrace and Eastern Macedonia . Serbia attacked south towards Skopje and Monastir and then turned west to present - day Albania , reaching the Adriatic , while a second Army captured Kosovo and linked with the Montenegrin forces . Greece ' s main forces attacked from Thessaly into Macedonia through the Sarantaporo strait and after capturing Thessaloniki on 12 November ( on 26 October 1912 , O . S . ) expanded its occupied area and linked up with the Serbian army to the northwest , while its main forces turned east towards Kavala , reaching the Bulgarians . Another Greek army attacked into Epirus towards Ioannina . In the naval front the Ottoman fleet twice exited the Dardanelles and was twice defeated by the Greek Navy , in the battles of Elli and Lemnos . Greek dominance on the Aegean Sea made it impossible for the Ottomans to transfer the planned troops from the Middle East to the Thracian ( against the Bulgarian ) and to the Macedonian ( against the Greeks and Serbians ) fronts . According to the E . J . Erickson the Greek Navy also played a crucial , albeit indirect role , in the Thracian campaign by neutralizing no less than three Thracian Corps ( see First Balkan War , the Bulgarian theater of operations ) , a significant portion of the Ottoman Army there , in the all - important opening round of the war . After the defeating of the Ottoman fleet the Greek Navy was also free to liberate the islands of the Aegean . General Nikola Ivanov identified the activity of the Greek Navy as the chief factor in the general success of the allies . In January , after a successful coup by young army officers , the Ottoman Empire decided to continue the war . After a failed Ottoman counter - attack in the Western - Thracian front , Bulgarian forces with the help of the Serbian Army managed to conquer Adrianople while Greek forces managed to take Ioannina after defeating the Ottomans in the battle of Bizani . In the joint Serbian - Montenegrin theater of operation the Montenegrin army besieged and captured the Shkodra , ending the Ottoman presence in Europe west of the Çatalca line after nearly 500 years . The war ended with the Treaty of London on 30 ( 17 ) May 1913 . Second Balkan War . Though the Balkan allies had fought together against the common enemy , that was not enough to overcome their mutual rivalries . In the original document for the Balkans league , Serbia promised Bulgaria most of Macedonia . But after the war , Serbia and Greece revealed their plan to keep part of the promised territory . This act prompted the tsar of Bulgaria to invade his allies . The Second Balkan War broke out on 29 ( 16 ) June 1913 when Bulgaria attacked its erstwhile allies in the First Balkan War , Serbia and Greece , while Montenegro , Romania and the Ottoman Empire intervened later against Bulgaria . When the Greek army entered Thessaloniki in the First Balkan War ahead of the Bulgarian 7th division by only a day , they were asked to allow a Bulgarian battalion to enter the city . Greece accepted in exchange for allowing a Greek unit to enter the city of Serres . The Bulgarian unit that entered Thessaloniki turned out to be a 48 , 000 - strong division instead of the battalion , something which caused concern among the Greeks , who viewed it as a Bulgarian attempt to establish a condominium over the city . In the event , due to the urgently needed reinforcements in the Thracian front , Bulgarian Headquarters was soon forced to remove its troops from the city ( while the Greeks agreed by mutual treaty to remove their units based in Serres ) and transport them to Dedeağaç ( modern Alexandroupolis ) , but still it left behind a battalion that started fortifying its positions . Greece had also allowed the Bulgarians to control the stretch of the Thessaloniki - Constantinople railroad that lay in Greek - occupied territory , since Bulgaria controlled the largest part of this railroad towards Thrace . After the end of the operations in Thrace — and confirming Greek concerns — Bulgaria was not satisfied with the territory it controlled in Macedonia and immediately asked Greece to relinquish its control over Thessaloniki and the land north of Pieria , effectively handing over all Aegean Macedonia . These unacceptable demands together with the Bulgarian refusal to demobilize its army after the Treaty of London had ended the common war against the Ottomans and alarmed Greece , which decided also to maintain its army ' s mobilization . Similarly , in northern Macedonia , the tension between Serbia and Bulgaria due to later aspirations over Vardar Macedonia generated many incidents between the nearby armies , prompting Serbia to maintain its army ' s mobilization . Serbia and Greece proposed that each of the three countries reduce its army by one fourth , as a first step to facilitate a peaceful solution , but Bulgaria rejected it . Seeing the omens , Greece and Serbia started a series of negotiations and signed a treaty on 1 June ( 19 May ) 1913 . With this treaty , a mutual border was agreed between the two countries , together with an agreement for mutual military and diplomatic support in case of a Bulgarian or / and Austro - Hungarian attack . Tsar Nicholas II of Russia , being well informed , tried to stop the upcoming conflict on 8 June , by sending an identical personal message to the Kings of Bulgaria and Serbia , offering to act as arbitrator according to the provisions of the 1912 Serbo - Bulgarian treaty . But Bulgaria , by making the acceptance of Russian arbitration conditional , in effect denied any discussion and caused Russia to repudiate its alliance with Bulgaria ( see Russo - Bulgarian military convention signed 31 May 1902 ) . The Serbs and the Greeks had a military advantage on the eve of the war because their armies confronted comparatively weak Ottoman forces in the First Balkan War and suffered relatively light casualties while the Bulgarians were involved in heavy fighting in Thrace . The Serbs and the Greeks had time to fortify their positions in Macedonia . The Bulgarians also held some advantages , controlling internal communication and supply lines . On 29 ( 16 ) June 1913 General Savov , under direct orders of tsar Ferdinand I , issued attacking orders against both Greece and Serbia without consulting the Bulgarian government and without any official declaration of war . During the night of 30 ( 17 ) June 1913 they attacked the Serbian army at Bregalnica river and then the Greek army in Nigrita . The Serbian army resisted the sudden night attack , while most of soldiers did not even know who they are fighting with , as Bulgarian camps were located next to Serbs and were considered allies . Montenegro ' s forces were just a few kilometers away and also rushed to the battle . The Bulgarian attack was halted . The Greek army was also successful . It retreated according to plan for two days while Thessaloniki was cleared of the remaining Bulgarian regiment . Then the Greek army counter - attacked and defeated the Bulgarians at Kilkis - Lahanas ( Kukush ) , after which the mostly Bulgarian town was destroyed and its population expelled . The Greek army destroyed altogether 161 Bulgarian villages and massacred thousands of inhabitants . Following the capture of Kilkis , the Greek army ' s pace was not quick enough to prevent the destruction of Nigrita , Serres , and Doxato and massacres of non - combatant Greek inhabitants at Demir Hisar and Doxato by the Bulgarian army . The Greek army then divided its forces and advanced in two directions . Part proceeded east and occupied Western Thrace . The rest of the Greek army advanced up to the Struma River valley , defeating the Bulgarian army in the battles of Doiran and Mt . Beles , and continued its advance to the north towards Sofia . In the Kresna straits the Greeks were ambushed by the Bulgarian 2nd and 1st Army newly arrived from the Serbian front that had already taken defensive positions there following the Bulgarian victory at Kalimanci . By 30 July the Greek army was outnumbered by the counter - attacking Bulgarian army , which attempted to encircle the Greeks in a Cannae - type battle , by applying pressure on their flanks . The Greek army was exhausted and faced logistical difficulties . The battle was continued for 11 days , between 29 July and 9 August over 20 km of a maze of forests and mountains with no conclusion . The Greek King , seeing that the units he fought were from the Serbian front , tried to convince the Serbs to renew their attack , as the front ahead of them was now thinner , but the Serbs rejected it . By then , news came of the Romanian advance toward Sofia and its imminent fall . Facing the danger of encirclement , Constantine realized that his army could no longer continue hostilities , agreed to Eleftherios Venizelos ' proposal and accepted the Bulgarian request for armistice as this had been communicated through Romania . Romania had raised an army and declared war on Bulgaria on 10 July ( 27 June ) as it had from 28 ( 15 ) June officially warned Bulgaria that it would not remain neutral in a new Balkan war , due to Bulgaria ' s refusal to cede the fortress of Silistra as promised before the First Balkan war in exchange for Romanian neutrality . Its forces encountered little resistance and by the time the Greeks accepted the Bulgarian request for armistice they had reached Vrazhdebna , 7 miles from the center of Sofia . Seeing the military position of the Bulgarian army the Ottomans decided to intervene . They attacked and finding no opposition , managed to recover eastern Thrace with its fortified city of Adrianople , regaining an area in Europe which was only slightly larger than the present - day European territory of the Republic of Turkey . Reactions among the Great Powers during the wars . The developments that led to the First Balkan War did not go unnoticed by the Great Powers , but although there was an official consensus between the European Powers over the territorial integrity of the Ottoman Empire , which led to a stern warning to the Balkan states , unofficially each of them took a different diplomatic approach due to their conflicting interests in the area . As a result , any possible preventive effect of the common official warning was cancelled by the mixed unofficial signals , and failed to prevent or to stop the war : The Second Balkan war was a catastrophic blow to Russian policies in the Balkans , where Russia had focused its interests for access to the " warm seas " for centuries . First , it marked the end of the Balkan League , a vital arm of the Russian system of defense against Austria - Hungary . Second , the clearly pro - Serbian position Russia had been forced to take in the conflict , mainly due to Bulgaria ' s uncompromising aggressiveness , caused a permanent break - up between the two countries . Accordingly , Bulgaria reverted its policy to one closer to the Central Powers ' understanding over an anti - Serbian front , due to its new national aspirations , now expressed mainly against Serbia . As a result , Serbia was isolated militarily against its rival Austria - Hungary , a development that eventually doomed Serbia in the coming war a year later . But most damaging , the new situation effectively trapped Russian foreign policy : After 1913 , Russia could not afford losing its last ally in this crucial area and thus had no alternatives but to unconditionally support Serbia when the crisis between Serbia and Austria broke out in 1914 . This was a position that inevitably drew her , although unwillingly , into a World War with devastating results for her , since she was less prepared ( both militarily and socially ) for that event than any other Great Power . Austria - Hungary took alarm at the great increase in Serbia ' s territory at the expense of its national aspirations in the region , as well as Serbia ' s rising status , especially to Austria - Hungary ' s Slavic populations . This concern was shared by Germany , which saw Serbia as a satellite of Russia . This contributed significantly to the two Central Powers ' willingness to go to war as soon as possible . Finally , when a Serbian backed organization assassinated the heir of the Austro - Hungarian throne , causing the 1914 July Crisis , nobody could stop the conflict and the First World War broke out . Aftermath . Russian demographer Boris Urlanis estimated in " Voini I Narodo - Nacelenie Europi " ( 1960 ) that in the first and second Balkan wars there were 122 , 000 killed in action , 20 , 000 dead of wounds , and 82 , 000 dead of disease . See also . Since the area has been referred to as the Balkans , notable conflicts have included the following : n