During the July Crisis of 1914 Mišić effectively deputised for the ailing Putnik (then recuperating at a spa in Hungary). Defending against the Austro-Hungarian invasion of Serbia, Mišić (who had emerged from retirement to do so) was placed in command of the Serbian First Army; in December 1914, he won a decisive victory at the Battle of Kolubara that resulted in the humiliating expulsion of Austro-Hungarian forces from Serbia. He was subsequently promoted to the rank of Field Marshal in recognition of his efforts in winning such a sweeping Serbian victory.