Serbian Despotate
In 1439, when he was returning from his trip to Mecca, he was ordered by the sultan to join forces of Şihabeddin Pasha and besiege Novo Brdo, important fortified mining town of Serbian Despotate. On 6 August 1439 the Ottoman forces under Ishak-Beg defeated forces of Serbian Despotate in a battle fought near Novo Brdo. In November 1443 he commanded one of Ottoman armies during the Battle of Niš which ended with Ottoman defeat.