The historian Nevra Necipoğlu highlights the reference to the Byzantine emperor as "father" by Süleyman throughout the treaty, indicating the remarkable reversal of positions brought about by the Battle of Ankara: from tributary Ottoman vassals teetering at the verge of extinction, after Ankara the Byzantines gained a certain advantage over the Ottomans, and managed to retain it for several years through adroit use of diplomacy and switching support between the rival Ottoman princes.[27] In 1411, Süleyman was overthrown and killed by his brother, Musa, who proceeded to capture most of the territories ceded to the Byzantines in Macedonia, Thessaly, and Thrace. However, after Musa was defeated by Mehmed I in 1413, bringing an end to the Ottoman civil war the new Sultan confirmed anew the provisions of the treaty of Gallipoli, and his position as "obedient son" of Emperor Manuel, and upheld them until his death in 1421.[28][29]