After the Austrian army of Michael von Melas invested a French army in Genoa during April 1800, Ott was given command of the siege operations. Ordered to raise the Siege of Genoa on 2 June, he disobeyed orders and remained in position. As he hoped, a few hours later, André Masséna asked for terms and formally surrendered to Ott on 4 June. In the bitterly fought Battle of Montebello on 9 June, a French force led by Jean Lannes defeated Ott's corps. He had fought the battle against orders. When the Austrian chief of staff begged him to withdraw at the beginning of the action, Ott replied, "My outposts are attacked. I march to succor them."