In the 15th century, the Ottoman Empire established itself in the Balkans with no significant resistance offered by local Christian nobles. Many of them were still fighting amongst themselves and didn't see the Ottoman advance as a threat to their power. Although a civil war broke out between Bayezid I's sons in 1402–13, none of the Christian noblemen in the Balkans at the time seized the opportunity to repel the Ottomans; on the contrary, Bulgarians, Serbs and Hungarians even helped the future Sultan Mehmed I seize power, by participating as his allies in the final battle against his brother. After the Ottoman civil war was over in favour of Mehmed I, his forces captured Kruja from the Thopia in 1415, Berat in 1417 from the Muzaka, Vlora and Kanina in 1417 from the widow of Balša III and Gjirokastër in 1418 from the Zenevisi. Under pressure from the Ottoman Empire and the Republic of Venice, the Albanian Principalities began to . Some Albanian nobility revolted in 1432–36.