The involvement of the Belgian Congo (the modern-day Democratic Republic of the Congo) in World War II began with the German invasion of Belgium in May 1940. Despite Belgium's surrender, the Congo remained in the conflict on the Allied side, administered by the Belgian government in exile.
Economically, the Congo provided much-needed raw materials such as copper and rubber to the United Kingdom and the United States. Uranium from the colony was used to produce the first atomic bombs. At the same time, a large supply of the territory's industrial diamonds were smuggled to Nazi Germany with the complicity of Belgian business executives. The Congo also financially supported the Belgian government in exile. Militarily, Congolese troops of the Force Publique fought alongside British forces in the East African Campaign, and a Congolese medical unit served in Madagascar and in the Burma Campaign. Congolese formations also acted as garrisons in Egypt, Nigeria and Palestine.
The increasing demands placed on the Congolese population by the colonial authorities during the war, however, provoked strikes, riots and other forms of resistance, particularly from the indigenous Congolese. These were repressed, often violently, by the Belgian colonial authorities. The Congo's comparative prosperity during the conflict led to a wave of post-war immigration from Belgium, bringing the white population to 100,000 by 1950, as well as a period of industrialisation that continued throughout the 1950s. The role played by Congolese uranium during the hostilities caused the country to be of interest to the Soviet Union during the Cold War.