On 12 June 1812 Napoleon invaded Russia with a Grande Armée of nearly 700,000 troops. After the measured victories at Smolensk and Borodino Napoleon occupied Moscow, only to find it burned by the retreating Russian army. He was forced to withdraw. On the march back his army was harassed by Cossacks, and suffered disease and starvation. Only 20,000 of his men survived the campaign. By 1813 the tide had begun to turn from Napoleon. Having been defeated by a seven nation army at the Battle of Leipzig in October 1813, he was forced to abdicate after the Six Days' Campaign and the occupation of Paris. Under the Treaty of Fontainebleau he was exiled to the island of Elba. He returned to France on 1 March 1815 (see Hundred Days), raised an army, but was finally defeated by a British and Prussian force at the Battle of Waterloo on 18 June 1815 and the Bourbons returned to power.