Meanwhile, an anti-Ottoman crusade led by the Hungarian King Sigismund of Luxemburg failed at the Battle of Nicopolis on 25 September 1396, but the Ottomans were themselves crushingly defeated by Timur at the Battle of Ankara in 1402. Manuel II had sent 10 ships to help in the Crusade of Nicopolis. As the sons of Bayezid I struggled with each other over the succession in the Ottoman Interregnum, John VII was able to secure the return of the European coast of the Sea of Marmara and of Thessalonica to the Byzantine Empire in the Treaty of Gallipoli. When Manuel II returned home in 1403, his nephew duly surrendered control of Constantinople and received as a reward the governorship of newly recovered Thessalonica. The treaty also regained from the Ottomans Mesembria (1403–1453), Varna (1403–1415), and the Marmara coast from Scutari to Nicomedia (between 1403–1421).