On 1 March 1815 Napoleon Bonaparte escaped from his imprisonment on the isle of Elba, and launched a bid to recover his empire. A confederation of European powers pledged to stop him. During the period known as the Hundred Days Napoleon chose to confront the armies of Prince Blücher and the Duke of Wellington in what has become known as the Waterloo Campaign. He was decisively defeated by the two allied armies at the Battle of Waterloo, which then marched on Paris forcing Napoleon to abdicate for the second time. However Russia, Austria and some of the minor German states also fielded armies against him and all of them also invaded France. Of these other armies the ones engaged in the largest campaigns and saw the most fighting were two Austrian armies: The Army of the Upper Rhine and the Army of Italy.