The Russian Empire was a state that existed from 1721 until overthrown by the short-lived liberal February Revolution in 1917. One of the largest empires in world history, stretching over three continents, the Russian Empire was surpassed in landmass only by the British and Mongol empires. It played a major role in 1812–14 in defeating Napoleon's ambitions to control Europe, and expanded to the west and south. It was often in conflict with the Ottoman Empire (which in turn was usually protected by the British).