"There are certain things in war of which the commander alone comprehends the importance. Nothing but his superior firmness and ability can subdue and surmount all difficulties." - Napoleon Bonaparte. In April of 1809, Austria took advantage of French preoccupation with Portugal by attacking Napoleon's German ally, Bavaria. New reforms in the Austrian army, including reorganization, as well as Napoleon¡¦s interest in fighting the British on the Iberian Peninsula fueled Austria's desire for revenge for having suffered numerous sharp defeats at French hands. The Austrians quickly pushed aside French resistance in the region, until Napoleon himself arrived on the field. Taking immediate action, he threw his troops across the Danube and struck at a surprised Austrian foe, cutting it in two. Marching into Vienna, Napoleon sought a decisive battle with Charles's army. Poor weather combined with a torrential river caused a large portion of France's army to be caught on the wrong side of the river as revitalized Austrian troops hit them hard. Eventually Napoleon managed to extract his men from the danger, but not after having suffered nearly 21,000 casualties to the Austrian's 23,000. While the myth of French invincibility had been credibly destroyed, not two days later Napoleon crushed the Austrians at Wagram, inflicting 40,000 casualties and forcing Austria to sue for peace and join his vaunted Continental System.