 The Austro @-@ Hungarians reached the Kolubara on 16 November and launched an assault against Serbian defensive positions there the following day . The Serbs managed to force the Austro @-@ Hungarians back and over the course of the next five days , the two armies fought a series of battles under heavy rain and snowfall . Both sides suffered heavy casualties , with a large number of soldiers succumbing to frostbite and hypothermia . 
