Re flags can signify a warning, martial law, defiance, or left-wing politics. The earliest citation for "red flag" in the Oxford English Dictionary is from 1602 and shows that at that time the flag was used by military forces to indicate that they were preparing for battle. It has been associated with left-wing politics since the French Revolution. The Labour Party in Britain and the French Socialist Party use it. The red flag became a symbol of communism as a result of its use by the Paris Commune of 1871. The flags of several communist nations, including China and Vietnam, have red backgrounds.