In 1545, Bagrat and his ally Luarsab I of Kartli suffered a bitter defeat at the Battle of Sokhoista in 1545. As a result, Samtskhe wrested of Bagrat’s control, and came under the Ottoman hegemony. In the following years, the principalities of Mingrelia and Guria also asserted their de facto independence from the crown of Imereti, further reducing the royal power. In 1555, in the Treaty of Amasya, the Ottoman and Persian empires divided Georgia, with Imereti falling into the Ottoman sphere of influence. Bagrat attempted to disrupt the Turco-Persian deal by pushing claims to the town of Surami which lay in the Persian zone in eastern Georgia. The move brought to nothing, however, and Bagrat was forced to pay tribute to the Ottomans. He died in 1565 and was succeeded by his son, George II.