Which Countries Were Allies of the British in World War II? When World War II erupted in September 1939, following Nazi Germany’s invasion of Poland, the United Kingdom found itself once again at the center of a vast global conflict. Unlike World War I, this conflict would spread even wider, engulfing nations across Europe, Asia, Africa, and the Pacific. To confront the Axis Powers — mainly Nazi Germany, Fascist Italy, and Imperial Japan — Britain relied heavily on a broad coalition of allies. Together, these countries formed what we commonly call the Allies of World War II . But who exactly were Britain’s allies, and what roles did they play? Let’s take a deeper look. The Major Allies 1. The United States of America Although initially neutral, the United States became a critical ally of Britain. The U.S. began by providing extensive material support through the Lend-Lease Act of 1941, which supplied Britain with food, oil, tanks, planes, and other crucial war materials. After t...