Stock Photo - 'Battle of Essling - Death of Montebello', 21 May 1809, (c1835). On 20 May, the IV Corps of Napoleon's army under Marshal Massena formed a bridgehead to check for enemy troops. By the next morning, more than 24,000 men with 60 cannon were occupying the villages of Aspern and Essling in Austria. The first thing the French command knew about the Austrian army was when more than 95,000 troops, supported by 200 cannon, moved against them. Driven out on several occasions, the French soldiers always managed to retake them at the point of a bayonet. Knowing he did not have enough men to break the enemy, the French emperor ordered a withdrawal to the Aspern-Essling line where a renewed series of Austrian attacks forced him to pull back on to Lobau Island. The repositioning took most of the night to achieve, but it was done in good order and when the final troops made the crossing the bridge was taken down. While not a true defeat, Aspern-Essling marked the first serious reverse suffered by Bonaparte at the hands of his foes. More than 21,000 French soldiers became casualties and the army suffered the grievous loss of one of its finest commanders, when Marshal Jean Lannes (Duke of Montebello) died after losing a leg to a cannonball wound.