In the first phase of the war the Ottomans had been able to conquer most of the Caucasus. Osman Pasha (Özdemir Pasha’s son) was appointed as the governor of the newly conquered territories. The capital of his province was Derbend at the Caspian coast. However, after the Ottoman army returned to its main base in Istanbul, the Persians under Imam Kulu began to regain some of their former territories. Although an army from the Crimean Khanate (which was an Ottoman vassal) under Mehmet Giray was sent to Caucasus in summer 1579 as a reinforcement, they returned to Crimea in the autumn, leaving Osman Pasha alone. Consequently, Osman Pasha had to retreat to North Caucasus. In 1582,the Ottoman Porte sent a second reinforcing force under Cafer Pasha, the governor of Caffa, to restore Ottaman domina