In April 1809, Archduke John quickly invaded Venetia in northeastern Italy. On 15 April at Pordenone, the Austrian advance guard routed the French rear guard, inflicting heavy losses. Undeterred by this setback and believing he enjoyed a numerical superiority over his opponents, Eugène attacked the Austrians east of Sacile the following day. Though the two sides were equal in numbers of foot soldiers, the Austrians possessed a two-to-one advantage in cavalry, and this turned out to be a key factor in their victory.