The main objective of the Campaign was to conquer the South Caucasus, most of which, at the time, belonged to or was subject to the Safavid Empire. On August 7, the Ottomans crossed the Georgian border, namely the Samtskhe-Saatabago principality. Georgians fought fiercely, but political fragmentation rendered them incapable of stopping the Ottoman advance. On the August 9, 1578, Turkish armies defeated the coalition of Irano-Georgian forces in the Battle of Çıldır. On the August 10, some Samtskhian nobles, including the brother of the ruler, accepted the Ottoman vassalage and in so doing, greatly aided them in the conquest of their Principality. Ottomans continued their expansion and by the August 24 took Tbilisi, the capital of the Kingdom of Kartli as well. Turks also established territorial units with Ottoman officials in the conquered areas, for example - Beylerbeylik of Tbilisi (Kartli), Sanjak of Gori, Eyalet of Childir and others. King of Kakheti, Alexander acted wisely and made peace with the Ottomans on September 1, agreeing on the annual tributes. Because of this agreement, Kingdom of Kakheti managed to escape the war completely unharmed. After this, Lala Mustafa Pasha headed to Shirvan, which he sought to conquer. After campaigning in the eastern Caucasus, Mustafa returned to Erzurum by crossing Kartli and Samtskhe. Georgians started a number of uprisings against their new Ottoman overlords. Shah of Iran, exploiting the weakness of Ottomans, released Simon I of Kartli, who earlier fought against Safavid domination, from captivity. Safavids hoped that Simon would now start war against the Turks and their expectations came true, ending the short lived Ottoman domination in the Caucasus and allowing them to install their puppet David XI on the throne of Kartli.