 He continued to maintain a defensive posture, as he thought that offensive action would leave either Mantua or the Tyrolean border too weakly defended.It was not until early April that the Austrian army began marching out to face the allies, massing along the Mincio River.Prince Eugene of Savoy, in a letter dated April 26, ordered Mercy to begin the campaign; total Austrian forces in northern Italy had grown to more than 55,000.