The Second World War broke out in September 1939, with both Britain and France declaring war on Germany after the German Army invaded Poland. Italy launched an invasion of Egypt, then a British Protectorate, shortly after entering the war on Germany's side in June 1940. The brigade fought in many of the major battles in North Africa, including Operation Crusader in November, fighting at Sidi Rezegh to try to relieve the Commonwealth forces in the port of Tobruk, besieged by Axis forces.