Roughly twenty-one years after the end of World War I, the second world war began. World War II found many of the same allies of World War I teaming up against the reformed Central Powers, which were renamed the Axis Powers in World War II. As before, Great Britain and France led the allies at the start, this time joined by Poland, a country that did not exist as an independent nation until the end of WWI. Independent nations of the British Empire, such as Canada, Australia, and South Africa, joined the Allies shortly thereafter. Over time, more than twenty Allies would join the cause as the number of countries involved in WWII continued to expand, engulfing even countries that have no military.
The Big Three Allies and the Four Powers of World War II
Three of the most powerful Allies entered the war—or at least the Allied cause—late, but had a massive impact when they did. First of these was Russia, which actually began WWII as one of the Axis Powers, having signed a non-aggression pact with Germany. In fact, Russia had assisted Germany in its initial invasion of Poland in 1939. However, Germany broke the non-aggression pact itself and attacked Russia in 1941, prompting Russia to switch its allegiance to the Allies.
As it had in the first World War, the United States spent the early portion of World War II attempting to distance itself from the affairs of Europe and join the list of countries that remained neutral in WWII. That all changed when the Japanese bombed the U.S. Naval base at Pearl Harbor, Hawaii in December 1941. In response, the United States entered the war in earnest, participating heavily in both the European and Pacific fronts.
China also joined the Allies in December 1941, an important development even though the country had already been at war with Axis power Japan since 1937. The United Kingdom, Russia, and the United States would come to be known as the "Big Three," and also (with China included) as the "Four Powers." They remain military powers today, with three of the largest militaries of any country on Earth, as well as some of the largest nuclear arsenals in the world. Once World War II ended, the Allies would establish the United Nations, an organization that today includes 193 countries and two observer states.
List of Allied Countries in World War II:
|Country||Date Joined||Country||Date Joined||Country||Date Joined|
|Argentina||27 March 1945||Finland*||15 Sept. 1944||Oman||10 Sept. 1939|
|Australia||3 Sept. 1939||France||3 Sept. 1939||Panama||7 Dec. 1941|
|Belgium||10 May 1940||Greece||28 Oct 1940||Paraguay||7 Feb. 1945|
|Bolivia||7 Apr. 1943||Guatemala||9 Dec. 1941||Peru||12 Feb. 1945|
|Brazil||22 Aug. 1942||Haiti||8 Dec 1941||Philippines||8 Dec 1941|
|British India||3 Sept. 1939||Honduras||8 Dec. 1941||Poland||1 Sept. 1939|
|Bulgaria*||8 Sept. 1944||Iran||9 Sept. 1943||Romania*||25 Aug. 1944|
|Canada||10 Sept. 1939||Iraq||16 Jan. 1943||Saudi Arabia||1 Mar. 1945|
|Chile||11 April 1945||Lebanon||27 Feb. 1945||South Africa||6 Sept. 1939|
|China||9 Dec 1941||Italy*||10 Oct. 1943||South Korea*||10 Dec. 1941|
|Colombia||26 July 1943||Liberia||27 Jan. 1944||Soviet Union||22 June 1941|
|Costa Rica||8 Dec. 1941||Luxembourg||10 May 1940||Syria||26 Feb. 1945|
|Cuba||9 Dec. 1941||Mexico||22 May 1942||Turkey||23 Feb. 1945|
|Czechoslovakia*||16 Dec. 1941||Mongolia||1 Aug 1945||United Kingdom||3 Sept. 1939|
|Denmark||8 Apr. 1940||Nepal||4 Sept. 1939||United States||8 Dec. 1941|
|Dominican Rep.||8 Dec. 1941||Netherlands||10 May 1940||Uruguay||15 Feb. 1945|
|Ecuador||2 Feb. 1945||New Zealand||3 Sept. 1939||Venezuela||15 Feb. 1945|
|Egypt||24 Feb. 1945||Nicaragua||8 Dec. 1941||Vietnam (Viet Minh)||7 Dec. 1941|
|El Salvador||8 Dec. 1941||Norway||8 Apr. 1940||Yugoslavia||6 Apr. 1941|
|Ethiopia||14 Dec. 1942|
- Bulgaria began the war as an Axis nation.
- Czechoslovakia's legitimate government declarted its allegiance while in exile, as the country was occupied.
- Finland fought alongside Germany and against Russia in the Continuation War from 1941-1944 and did not declare war on Germany until 3 March 1945. However, the declaration was made retroactive to 15 September 1944.
- Italy and Romania began the war as Axis nations.
- South Korea's government was provisional at the time of its declaration.
- Vietnam's allegiance was declared by the Viet Minh, a government that was revolutionary at the time.