British Empire in World War II

Propaganda poster promoting the joint war effort of the British Empire and Commonwealth, 1939.

When the United Kingdom declared war on Germany at the outset of World War II it controlled to varying degrees numerous crown colonies, protectorates and the Indian Empire. It also maintained unique political ties to four semi-independent DominionsAustralia, Canada, South Africa, and New Zealand—as part of the Commonwealth. 

In 1939 the British Empire was a global power, with direct or de facto political and economic control of 25% of the world’s population, and 30% of its land mass. 

The contribution of the British Empire and Commonwealth in terms of manpower and materiel was critical to the Allied war effort. From September 1939 to mid-1942 Britain led Allied efforts in almost every global military theatre. Commonwealth forces (United Kingdom, Colonial, Imperial and Dominion), totalling close to 15 million serving men and women, fought the German, Italian, Japanese and other Axis armies, air forces and navies across Europe, Africa, Asia, and in the Mediterranean Sea and the Atlantic, Indian, Pacific and Arctic Oceans. Commonwealth forces fought in Britain, and across Northwestern Europe in the effort to slow or stop the Axis advance. Commonwealth airforces fought the Luftwaffe to a standstill over Britain, and its armies fought and destroyed Italian forces in North and East Africa and occupied several overseas colonies of German-occupied European nations. Following successful engagements against Axis forces, Commonwealth troops invaded and occupied Libya, Italian Somaliland, Eritrea, Ethiopia, Iran, Iraq, Syria, Lebanon, Iceland (Denmark), the Faroe Islands (Denmark), and Madagascar.

Although the British Empire and the Commonwealth countries all emerged from the war as victors, and the conquered territories were returned to British rule, the costs of the war and the nationalist fervour that it had stoked became a catalyst for the decolonisation which took place in the following decades.

File:Flag of the United Kingdom.svg

Declaration of war against Germany

On 1 September 1939, Germany invaded Poland. Two days later, on 3 September, after a British ultimatum to Germany to cease military operations was ignored, Britain and France declared war on Germany. Britain’s declaration of war automatically committed India, the Crown colonies, and the protectorates, but the 1931 Statute of Westminster had granted autonomy to the Dominions so each decided their course separately.

Australian Prime Minister Robert Menzies immediately joined the British declaration on 3 September, believing that it applied to all subjects of the Empire and Commonwealth. New Zealand followed suit simultaneously, at 9.30 pm on 3 September (local time), after Peter Fraser consulted the Cabinet; although as Chamberlain’s broadcast was drowned by static, the Cabinet (led by Fraser as Prime Minister Michael Savage was terminally ill) delayed until the Admiralty announced to the fleet a state of war, then backdated the declaration to 9.30 pm. South Africa took three days to make its decision (on 6 September), as the Prime Minister General J. B. M. Hertzog favoured neutrality but was defeated by the pro-war vote in the Union Parliament, led by General Jan Smuts, who then replaced Hertzog. Canadian Prime Minister Mackenzie King declared support for Britain on the day of the British declaration, but also stated that it was for Parliament to make the formal declaration, which it did so one week later on 10 September. Ireland, which had been a dominion until 1937, remained neutral. 

Kenya Royal Naval Volunteer Reserve 1945.

British (red) and Belgian (Orange) colonies fought with the Allies. Italian (green) with the Axis. French colonies (dark blue) fought with the Allies until the Fall of France after which some supported Vichy and some the Free French. Portuguese (brown) and Spanish (teal) colonies remained neutral.


By the end of the war in August 1945, British Commonwealth forces were responsible for the civil and/or military administration of a number of non-Commonwealth territories, occupied during the war, including Eritrea, Libya, Madagascar, Iran, Iraq, Lebanon, Italian Somaliland, Syria, Thailand and portions of Germany, Austria and Japan. Most of these military administrations were handed over to old European colonial authorities or to new local authorities soon after the end of the hostilities. Commonwealth forces administered occupation zones in Japan, Germany and Austria until 1955. World War II confirmed that Britain was no longer the great power it had once been, and that it had been surpassed by the United States on the world stage. Canada, Australia and New Zealand moved within the orbit of the United States. The image of imperial strength in Asia had been shattered by the Japanese attacks, and British prestige there was irreversibly damaged. The price for India’s entry to the war had been effectively a guarantee for independence, which came within two years of the end of the war, relieving Britain of its most populous and valuable colony. The deployment of 150,000 Africans overseas from British colonies, and the stationing of white troops in Africa itself led to revised perceptions of the Empire in Africa. 

Military histories of the British Empire’s colonies, dominions, mandates and protectorates 

The contributions from individual colonies, dominions, mandates, and protectorates to the war effort were extensive and global. Further information about their involvement can be found in the military histories of the individual colonies, dominions, mandates, and protectorates listed below.


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  2. albertrudolf · July 7, 2019
  3. Ellie Wolfe · July 7, 2019

    Reblogged this on Fascist Bostonian and commented:
    #worldwar2 #wwii


  4. germanicunity · July 11, 2019

    Reblogged this on Germanic Unity.


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