Of Serbian descent, Paul Dimich joined the Slavonian border guards in 1749 when he was 18 years old. He participated in the War of Succession, in which he advanced as far as the rank of captain, attended the siege of Ingolstadt, the battles of Striegau and Trautenau, and participated in the new organization that took place after the Peace of Aix-la-Chapelle in the Banat Military Frontier. Well before the beginning of the Seven Years' War, he was made major in the Slavic Gradiskaner regiments.