Behind the scenes the Irish state worked with the Allies; in 1940, the government agreed provisionally with Britain that it would accept the entry of British troops and put its own armed forces under their command should the Germans invade Ireland – see Plan W. There was a provisional German plan for an invasion of Ireland, known as Operation Green, but it was never carried out. Additionally, Irish fire fighters were sent to Northern Ireland to help fight the fires caused by the German bombing of Belfast in 1941 (See Belfast Blitz).