Article: Balkan Wars
Section: First Balkan War

Question: Who allied with Bulgaria at Adrianopole in the 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.