Ottoman capture of Adrianople

Sometime between 1361 and 1371, the Byzantine city of Adrianople was captured by the Ottoman Turks. The details and chronology are obscure and debated among modern scholars, with some authors making the hypothesis that the city was reconquered and that there were two different sieges.

After the fall of the city, it became the new capital of the Ottoman state as Edirne, which it remained until the Fall of Constantinople in 1453.

Background
By 1354, Ottoman forces were already settled in Gelibolu in European portion of the Byzantine Empire and they were advancing. Although they had to halt their advance because of the event known as Kidnapping of Şehzade Halil between 1357-1359, after Halil's rescue they resumed their advance. Main target of the advance was Adrianople, which was the third important Byzantine city (after Constantinople and Thessalonica).

Initial operations
Şehzade Murat (Future Murat I) was in charge of the operations. In 1359 he concentrated on the forts to the east of Edirne obviously to isolate the city from the capital. He captured Çorlu and Lüleburgaz. He also took precations to isolate the city from the south. He sent his two generals Hacı İlbey and Gazi Evrenos to Meriç River (Maritza) valley. Hacı İlbey captured Didymoteicho (now in Greece) Gazi Evrenos  captured Keşan. When Murat decided that the city was fully isolated he called back his generals for a general offensive.

Capture of the city
Murat's camp was in Babaeski, 55 km from Edirne. But vanguard units under Lala Şahin Pasha were much closer to the city and the Byzantine governor, supported by Bulgarians tried to raid the vanguard units in a location named Sazlıdere, 12 km south east of the city. But they were repelled. Although they were able to return to Edirne,  after a flood of the river, the demoralized Byzantine governor, left the city. Left to themselves, the city's residents decided to surrender conditionally. Murat agreed not to force religious conversion. Finally on 5 May 1361 Murat captured the city rather peacefully.

Date controversy
Other historians, relying on Byzantine and other sources, favour 1369 or even dates after 1371, the siege being directed not by Murat but by Turkish beys only nominally vassals to the Ottomans (since from 1366 to 1377 communications between Thrace and Anatolia were interrupted). The Ottomans could then perhaps have taken direct control of the city only in the late 1370's.

Edirne as a capital
Lala Şahin was declared the first beylerbey of Rumeli (Ottoman Thrace) and Murat moved to recently captured Didymeteicho to continue his operations. After his father's death and construction a palace in Edirne, he declared Edirne as the new capital.