Complex sentence: The main elements to face the Austro-Hungarians were the 1st, 2nd, 3rd and Užice armies, with a combined strength of approximately 180,000 men.
Split into simpler sentences: The main elements that would face the Austro-Hungarians were the 1st, 2nd, 3rd and Užice armies. These had a combined strength of approximately 180,000 men.