Who Were the Allied Powers?

The Allied Powers of World War II included many nations, but the “Big Three” were Great Britain, America, and the Soviet Union.

Jan 6, 2024By Matt Whittaker, BA History & Asian Studies
who were the allied powers
Soviet premier Joseph Stalin, US president Franklin Delano Roosevelt, and british Prime Minister Winston Churchill (left to right) at the Teheran Conference, 1943. (Library of Congress, LC-USZ62-32833.)


1942 was a pivotal year during World War II, marking the year the Allied Powers became official. America and the Soviet Union, attacked by an Axis power, joined Britain to become the dominant Allied signers. Other Allied countries, like France or Norway, contributed, but these three determined the strategy. Meanwhile, despite their involvement, China never officially joined.


Great Britain: The One That Never Wavered

Downed Bomber Salvaging 1940. Source: Imperial War Museum


Great Britain, alone of the Allied Powers, never hesitated during the war despite numerous defeats. The British Empire stood alone for nearly two years. In January 1942, all three countries became Allies under the United Nations Declaration. Led by the fiery, stubborn Prime Minister Winston Churchill, Britain and America fought the Axis successfully in North Africa, Italy, and later into Germany.


Britain offered much to the Allies, including a smaller but very experienced military, a large navy, and the Commonwealth’s natural resources. Britain’s Empire provided many locations that were used as bases for long-term campaigns. Britain, for example, became an island base for the D-Day invasions of France on June 6, 1944. By opening a second front, the Allies squeezed Germany from two directions, which caused a faster collapse and surrender in May 1945. 


Being one of the major powers, Great Britain participated in the Manhattan Project, helping to develop the atomic bomb. The British provided expertise, manpower, and technology and, after the war, received the bomb itself. Being a Project participant furthered Britain’s status as a world power. 


The Soviet Union

Operation Barbarossa Map 1941. Source: Onwar.com

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The Soviet Union’s violent entry into World War II resulted from Germany’s Operation Barbarossa in June 1941. The invasion happened despite the 1939 Molotov-Von Ribbentrop Pact. Germany and its allies had conquered vast parts of the country within six months. Stalin’s 1937 Purges of perceived threats eliminated his most experienced generals and aided his enemies. Of the Allied Powers, the Soviets suffered the greatest destruction, disruption, and loss of life.


The Soviet Union, like Britain, brought much to the Allied cause. The pros included a large military, a determined leader, and a good spy network. The Eastern Front tied down seventy-five percent of German forces but at considerable cost. Formally joining the Allies opened up a lifeline that was desperately needed. The Soviet Union readily accepted America’s Lend-Lease offer, which delivered eleven billion dollars’ worth of food, trains, explosives, much prized American trucks, and more. This aid gave Soviet soldiers items like boots, high-octane gasoline, and very durable trucks. These trucks gave the Red Army unheard-of mobility, helping to drive the Germans back.


1941 Lend Lease Bill. Source: National Archives


The Soviet Union never completely trusted their Allied partners; mutual low-key distrust remained. Stalin immediately pushed for a second front in the West as his country fought the Germans in Europe alone. Britain and America would not commit until 1944. Both feared Stalin might make a separate treaty with Germany and leave the war. Ever suspicious, the Soviet spy network even penetrated the Manhattan Project, sending vital information back that sped up Soviet postwar atomic development. Stalin feared the A-bomb would be used against him. 


The United States of America

P-63 fighter for Russia. Source: Wikimedia Commons.


During World War II, America became democracy’s arsenal. Some countries manufactured more of this or that, but none matched America’s industrial output. The U.S. manufactured sufficient materials to fight in the European and Pacific theaters plus readily supply their allies. For example, America built and provided over 300,000 planes from 1941 to 1945. The Allies used the Sherman tank, arguably the war’s best general tank.


All materials were provided through Lend-Lease, an agreement to repay the U.S. postwar. The program proved vital by distributing materials many occupied Allied countries could not. The America of 1940 was a place where isolationism predominated. Protected on both sides by oceans, the country could afford to be. Many people, conscious of World War I’s cost, thought to let the rest of the world fight. Not until December 7, 1941, did isolationism end.


Soviet and American meet 1945. Source: Wikimedia Commons


The Pearl Harbor attack enraged America like never before. American industry and people flexed their muscles, taking the fight to where needed. The 1942 U.N. agreement joined America with the Soviet Union and Great Britain. America benefitted immensely from being an Allied Power. Postwar, America’s economy boomed, turning the country into a superpower. Despite political differences, the Allies cooperated to keep the Axis from dominating the world. The Allied Powers were a coalition that worked when needed.

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By Matt WhittakerBA History & Asian StudiesMatt Whittaker is an avid history reader, fascinated by the why, how and when. With a B.A. in History and Asian Studies from University of Massachusetts, he does deep dives into medieval, Asian and military history. Matt’s other passion besides family is the long-distance Zen-like runs.