Battle_of_Essling

In the Battle of Aspern-Essling (21–22 May 1809), Napoleon crossed the Danube near Vienna, but the French and their allies were attacked and forced back across the river by the Austrians under Archduke Charles. It was the first time Napoleon had been personally defeated in a major battle, as well as his first defeat in 10 years since the Siege of Acre, and his first defeat as head of state.
Archduke Charles drove out the French but fell short of destroying their army. The Austrian artillery dominated the battlefield, firing 53,000 rounds compared to 24,300 French. The French lost over 20,000 men including one of Napoleon's ablest field commanders and closest friends, Marshal Jean Lannes.