The term "home front" covers the activities of the civilians in a nation at war. World War II was a total war; homeland military production became vital to both the Allied and Axis powers. Life on the home front during World War II was a significant part of the war effort for all participants and had a major impact on the outcome of the war. Governments became involved with new issues such as rationing, manpower allocation, home defense, evacuation in the face of air raids, and response to occupation by an enemy power. The morale and psychology of the people responded to leadership and propaganda. Typically women were mobilized to an unprecedented degree.

All of the powers used lessons from their experiences on the home front during World War I. Their success in mobilizing economic output was a major factor in supporting combat operations. Among morale-boosting activities that also benefited combat efforts, the home front engaged in a variety of scrap drives for materials crucial to the war effort such as metal, rubber, and rags. Such drives helped strengthen civilian morale and support for the war effort. Each country tried to suppress negative or defeatist rumors.

The major powers devoted 50–61 percent of their total GDP to munitions production. The Allies produced about three times as much in munitions as the Axis powers.

Source: Goldsmith data in Harrison (1988) p. 172

Source: Jerome B Cohen, Japan's Economy in War and Reconstruction (1949) p 354

The Allies called themselves the "United Nations" (even before that organization formed in 1945), and pledged their support to the Atlantic Charter of 1941. The Charter stated the ideal goals of the war: no territorial aggrandizement; no territorial changes made against the wishes of the people; restoration of self-government to those deprived of it; free access to raw materials; reduction of trade restrictions; global cooperation to secure better economic and social conditions for all; freedom from fear and want; freedom of the seas; and abandonment of the use of force, as well as the disarmament of aggressor nations.

The sudden German invasion of neutral Belgium in May 1940 led in a matter of 18 days to the collapse of the Belgian army; King Leopold obtained an armistice that involved direct German military administration. The King refused the government's demand that he flee with them to Britain; he remained as a puppet ruler under German control. The Belgian bureaucracy remained in place and generally cooperated with the German rulers. Two pro-German movements, the Flemish National Union comprising Flemish (Dutch-speaking) separatists and the Walloon (French-speaking) Rexists led by Léon Degrelle (1906–94), supported the invaders and encouraged their young men to volunteer for the German army. Small but active resistance movements, largely Communist, provided intelligence to the Allies. During the Holocaust in Belgium, the Nazis hunted down the 70,000 Jews living in Belgium, most of them refugees, and killed 29,000 of them.

The Germans expected to exploit Belgium's industrial resources to support their war machine. Their policies created severe shortages for the Belgian people, but shipped out far less than Germany had expected. They set up the "Armaments Inspection Board" in 1940 to relay munitions orders to factories; the Board came under the control of the German Minister of Armaments, Albert Speer in 1943, and had offices in industrial areas that were supposed to facilitate orders for materiél, and supervise production. However, factory production fell sharply after 1942. Although collaboration with the Nazis, especially among the Flemish, was evident in 1940, it soon faded in importance. Labor strikes and systematic sabotage slowed production, as did the emigration of workers to rural areas, Allied bombing, food shortages, and worker resentment of forced labor.