Allies of World War II
The Allies, later known formally as the United Nations, were an international military coalition formed during the Second World War (1939–1945) to oppose the Axis powers, led by Nazi Germany, the Empire of Japan, and Fascist Italy. Its principal members by 1941 were the United Kingdom, United States, Soviet Union, and China.
Membership in the Allies varied during the course of the war. When the conflict broke out on 1 September 1939, the Allied coalition consisted of Poland, the United Kingdom, and France, as well as their respective dependencies, such as British India. They were soon joined by the independent Dominions of the British Commonwealth: Canada, Australia, New Zealand and South Africa. Consequently, the initial alliance largely resembled that of the First World War.
As Axis forces began invading northern Europe and the Balkans, the Allies added Netherlands, Belgium, Norway, Greece, and Yugoslavia. The Soviet Union, which had a nonaggression pact with Germany and joined in its invasion of Poland, became an Allied member in June 1941 after being attacked by the Axis. The United States, while providing materiel support to the Allies from September 1940, remained formally neutral until the Japanese bombing of Pearl Harbor in December 1941, after which it declared war and officially joined the Allies. China was already at war with Japan since 1937 but formally joined the Allies in December 1941.
The Allies were led by the so-called "Big Three"—the United Kingdom, the Soviet Union, and the United States—which were the principal contributors of manpower, resources, and strategy, each playing a key role in achieving victory. A series of conferences between Allied leaders, diplomats, and military officials gradually shaped the makeup of the alliance, the direction of the war, and ultimately the postwar international order. Relations between the United Kingdom and the United States were especially close, with their bilateral Atlantic Charter forming the groundwork of the alliance.
The Allies became a formalized group upon the Declaration by United Nations on 1 January 1942, which was signed by 26 nations around the world; these ranged from minor powers far removed from the war, to governments exiled by Axis occupation. The Declaration officially recognized the Big Three and China as the "Four Powers", in acknowledgement of their central role in prosecuting the war; they were also referred to as the "trusteeship of the powerful" and later as the "Four Policemen" of the United Nations. Many more countries joint the following day and through the final days of the war, including colonies and former Axis nations.
After the war ended, the Allies, and the Declaration that bound them, would become the basis of the modern United Nations; one enduring legacy of the alliance is the permanent members of the U.N. Security Council, which is made up exclusively of the principal Allied powers that won the war.