When the fourth, combined German, Austro-Hungarian, and Bulgarian invasion force attacked Serbia in 1915, the First Army was tasked with defence of the western border of Serbia (along the river Drina). It faced mostly units of Austro-Hungarian Third Army and was mostly under less pressure then other Serbian units facing Germans or Bulgarians. Perhaps as a consequence of this Mišić was in favor of halting and making a final stand against the Central Powers forces when the High Command ordered retreat across Montenegro and Albania to Italian-held Durrës and Vlorë (at the time Serbian Army was defending itself in Kosovo from three sides and was in danger of becoming surrounded). However, he was overruled by other army commanders at their meetings at Peć, who decided to carry on the order of High Command.