The Campaign in Thrace

The First Balkan War was fought between Serbia, Bulgaria, Greece, and Montenegro (known as the Balkan League) and the Ottoman Empire. Montenegro opened hostilities by declaring war on Turkey on Oct. 8, 1912, and the other members of the league followed suit 10 days later. The Balkan League was soon victorious. In Thrace, the Bulgarians defeated the main Ottoman forces, advancing to the outskirts of Istanbul and laying siege to Edirne.
The bloody battle of Lule Burgas - Bunar Hisar gets good coverage in this excellent tactical study that forms part of the "Pall Mall military series". In terms of forces engaged it was the largest battle fought in Europe between the end of the Franco-Prussian War and the beginning of the First World War. Written by an officer who visited the battlefield and who was well acquainted with the Bulgarian Officer corps, he viewed the opening phase covered in this study from their point of view.
The war was a comprehensive and unmitigated disaster for the Ottomans, who lost 83% of their territories in Europe and 69% of their European population.