British Empire in World War II

Military history of the United Kingdom during World War IIDiplomatic history of World War II and When the United Kingdom declared war on Nazi Germany in September 1939 at the start of World War II, it controlled to varying degrees numerous crown colonies, protectorates, and India. It also maintained unique political ties to four of the five independent Dominions—Australia, Canada, South Africa, and New Zealand—as co-members (with the UK) of the then "British Commonwealth". In 1939 the British Empire and the Commonwealth together comprised a global power, with direct or de facto political and economic control of 25% of the world's population, and of 30% of its land mass. The contribution of the British Empire and Commonwealth in terms of manpower and materiel was critical to the Allied war-effort. From September 1939 to mid-1942, the UK led Allied efforts in multiple global military theatres. Commonwealth, Colonial and Imperial Indian forces, totalling close to 15 million serving men and women, fought the German, Italian, Japanese and other Axis armies, air-forces and navies across Europe, Africa, Asia, and in the Mediterranean Sea and the Atlantic, Indian, Pacific and Arctic Oceans. Commonwealth forces based in Britain operated across Northwestern Europe in the effort to slow or stop Axis advances. Commonwealth airforces fought the Luftwaffe to a standstill over Britain, and Commonwealth armies defeated Italian forces in East Africa and North Africa and occupied several overseas colonies of German-occupied European nations. Following successful engagements against Axis forces, Commonwealth troops invaded and occupied Libya, Italian Somaliland, Eritrea, Ethiopia, Iran, Iraq, Syria, Lebanon, Iceland, the Faroe Islands, and Madagascar. The Commonwealth defeated, held back or slowed the Axis powers for three years while mobilizing its globally-integrated economy, military, and industrial infrastructure to build what became, by 1942, the most extensive military apparatus of the war.