Russia–United Kingdom relations is the relationship between the Russian Federation and the United Kingdom. Spanning nearly five centuries, it has often switched from a state of alliance to rivalry or even war. The Russians and British were allies against Napoleon, and enemies in the Crimean War of the 1850s, and rivals in the Great Game for control of central Asia in the late 19th century. They were allies again in the world wars, although relations were strained by the Russian Revolution of 1917. They were at sword's point during the Cold War (1947-1991). Russian big businesses had strong connections with the City of London and British corporations during the late 1990s and 2000s.