When the United Kingdom declared war on Nazi Germany at the outset of World War II, the British Empire was a global superpower, with direct or de facto political and economic control of 25% of the world’s population, and 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. Close to 15 million serving men and women, fought across Europe, Africa, Asia, and in the Mediterranean Sea and the Atlantic, Indian, Pacific and Arctic Oceans. Commonwealth airforces fought the Luftwaffe to a standstill over Britain, and its armies fought and destroyed Italian forces in North and East Africa and occupied several overseas colonies of German-occupied European nations.
The Commonwealth defeated, held back or slowed the Axis powers for three years while mobilizing their globally integrated economy, military, and industrial infrastructure.These efforts came at the cost of 150,000 military deaths, 400,000 wounded, 100,000 prisoners, over 300,000 civilian deaths, and the loss of 70 major warships, 39 submarines, 3,500 aircraft, 1,100 tanks and 65,000 vehicles.
Britain became the nucleus of the Allied war effort in Europe. Canada delivered almost $4 billion in direct financial aid to the United Kingdom, while Australia and New Zealand began shifting to domestic production to provide material aid to US forces in the Pacific. Following the US entry into the war in December 1941, the Commonwealth and United States coordinated their military efforts and resources globally.