The Waterloo campaign was fought between the French Army of the North and two Seventh Coalition armies, an Anglo-allied army and a Prussian army. Initially the French army was commanded by Napoleon Bonaparte, but he left for Paris after the French defeat at the Battle of Waterloo. Command then rested on Marshals Soult and Grouchy, who were in turn replaced by Marshal Davout, who took command at the request of the French Provisional Government. The Anglo-allied army was commanded by the Duke of Wellington and the Prussian army by Prince Blücher.
The war between France and the Seventh Coalition came when the other European Great Powers refused to recognise Napoleon as Emperor of the French upon his return from exile on the island of Elba, and declared war on him, rather than France, as they still recognised Louis XVIII as the king of France and considered Napoleon a usurper. Rather than wait for the Coalition to invade France, Napoleon decided to attack his enemies and hope to defeat them in detail before they could launch their combined and coordinated invasion.