Macdonald's army moved north, reaching Rome on 16 May 1799 and Florence on 26 May. The most secure route to join the Army of Italy was via the west coast, but Macdonald opted to take the bolder and riskier route across the Apennine Mountains toward Piacenza. Macdonald accompanied the center column, composed of the divisions of Olivier and François Watrin, which marched from Pistoia to Modena. On 12 June, the center column attacked Prince Friedrich Franz Xaver of Hohenzollern-Hechingen's 4,000 infantry and 800 cavalry in the Battle of Modena. The Austrians suffered 2,000 casualties in this defeat, but in a chance encounter Macdonald was wounded by a party of cavalrymen. After the battle, Macdonald ordered the divisions of Olivier and Joseph Hélie Désiré Perruquet de Montrichard northward in a feint toward the Siege of Mantua. Consequently, these divisions missed the initial fighting at the Battle of Trebbia on 17–20 June.