The British Empire (comprising of the mainland 
United Kingdom and its territories) was among the 
biggest powers of the war. The British fought in 
the deserts of the Middle East, the seas of the 
Atlantic, and on the Western Front. Because of 
their vast manpower and resources, the Commonwealth 
forces were one of the largest Allied forces during 
the entire war, mounting major campaigns in the war's 
four year length. 