After the Russian Empire conquered the Crimean Khanate in 1783, Ushakov personally supervised the construction of a naval base in Sevastopol and the building of docks in Kherson. During the Russo-Turkish War (1787–92), he defeated the Ottomans at Fidonisi (1788), Kerch Strait (1790), Tendra (1790), and Cape Kaliakra (1791). In these battles, he demonstrated the ingenuity of his innovative doctrines in the art of naval warfare.