The reconquest of Gallipoli was a successful attempt by Amadeus VII, Count of Savoy, to take back Gallipoli after its capture by the Ottomans in 1354 following a disastrous earthquake.
Since 1354, the Turks had used the Dardanelles to cross over into Thrace in large numbers. Western Asia Minor had in the space of less than 100 years become the core of the Ottoman realm. As the Turks crossed over into Europe, they took town after town from the Byzantine Empire, which did not stop its own civil war until 1391 and exchanged the local Greeks for Turkish settlers, thereby giving the Turks a foot hold on the region that would last to this present day. Ultimately, Gallipoli was not as strategically important in 1366 as it had been in 1354 - Thrace was already an Ottoman stronghold. Even so, the Christians retained naval supremacy in the region, right until the early 15th century, so whilst there may have been Turks in Thrace, a war of attrition may have stemmed the tide in favour of Byzantium; without reinforcements from Asia Minor the Turks would have been overwhelmed.
Civil warfare was too distracting for Byzantium and Andronikos IV Palaiologos gave the keys to the Balkans to Murad in exchange for the Sultan's assistance. By 1377 Gallipoli was once more ferrying in Turkish settlers and destroying what little of the Byzantine power base was left.