Even though this is a difficult question to answer, I will try to answer it.

Adolf Hitler held the widely held view in the German Reich that Britain's entry into the First World War was the result of imperial competition aimed at eliminating the German Reich as an economic rival. He saw a high degree of autarky as necessary to have a free hand strategically and militarily. The memory of the very effective naval blockade by the Allies during the First World War also played a role. For a long time, the German Reich had been striving for a large-scale economy. In this plan, Germany would be the industrial heartland together with its industrialised neighbours France, Belgium and Bohemia. The peripheral countries would provide raw materials and food. The metropolitan economy was to provide a larger market with intensive trade relations, whereby increasing trade was to raise the employment rate and per capita income. Racial considerations also played a role in the idea of a large-scale economy. According to this, the people of the economic periphery were not capable of a higher economy for racial reasons. Following the concept of a large-scale economy, the German Reich had concluded several bilateral trade agreements with South-Eastern European countries since 1933 in accordance with the New Plan, which made more favourable conditions possible than the trade agreements with other industrialised countries, some of which demanded advance payment for imports from German trading partners who were short of foreign currency. These cooperative trade agreements were also of great benefit to the war economy. Hungary, Romania and Bulgaria exported between 40% and 50% of their total goods to the German Reich. For Romanian trade, petroleum in particular was a significant commodity; for Hungary, foodstuffs and armaments. German companies invested on a large scale in Hungary and thus indirectly helped with industrialisation.

Hitler's thinking circled in an outlandish universe and is difficult to grasp because of its irrationality. On the one hand, he saw a "Jewish world conspiracy" dominating the USA, Great Britain and the Soviet Union and encircling the German Reich. On the other hand, he believed that a high standard of living, as in the USA, could only be achieved through a large living space. He sought a racist Lebensraum policy in Poland and parts of the Soviet Union, with the aim of conquest and depopulation. This planning was diametrically opposed to the more traditional idea of a large-scale economy using the existing peripheral economies and, because of its senseless cruelty, resulted in the temporarily conquered eastern territories being of little use to the war economy of the German Reich, despite their size in terms of area and population.

In Italy, there were attempts to establish a large-scale economy of its own. However, this was difficult due to the strong expansion of German trade relations to South-Eastern Europe. Likewise, there were attempts to create synthetic industries important to the war effort through protectionism and subsidies, but the efforts fell well short of those of the German Reich. Overall, there were no adequate attempts in Italy to prepare economically for a prolonged war.

The Japanese war aims were primarily economic. Similar to the German Empire, the aim was to create its own large-scale economy, which was referred to as a coprosperity area, although here the focus was exclusively on strengthening the Japanese economy and not on radical social or racial goals. The Japanese economy would have formed the industrial core area and the peripheral economies would have been included primarily for the supply of raw materials and food production through trade agreements. Korea would have been responsible for rice supply, Manchuria for iron, coal and food, Roe (Province) for coal and cotton, Dutch India for oil and bauxite, Malaysia for tin and rubber and Dutch Formosa for sugar. The snag in the planning was that some mineral resources had not yet been tapped and the exploitation of the coprosperity zone thus required high investments in facilities and transport infrastructure in some cases, although for Japan both capital and the time factor were scarce commodities.

The Allies feared the economic consequences of a Second World War because, after the experiences of the First World War, they assumed that a costly war with high inflation and social unrest would inevitably lead to a worldwide recession after the end of the war. Concerns were greatest in the USSR, where the violent economic and social transformation to communism was generating unrest. On the other hand, since the spring of 1939, Stalin placed increasing emphasis on the Leninist doctrine of the inevitability of war against the capitalist states. According to Stalin's planning, the German-Soviet Non-Aggression Pact of August 1939 was to help the German Reich, France and England weaken each other in a long and bloody war of attrition, while the Soviet Union could rearm undisturbed. Russia had experienced in the First World War that a lack of war material led to very high losses of soldierly human lives. For Stalin, the industrialisation that was pushed at full speed also had the purpose of not losing the coming war again as a "battle of the machines" for greater weapons production. The Soviet Five-Year Plan for 1928-1932, with its goal of industrialising the Soviet Union, actually contributed significantly to the Soviet Union winning the German-Soviet War. Industrialisation made it possible to produce many more weapons and factories were built in areas of the Soviet Union that were beyond the reach of German troops, despite the initial successes of the Barbarossa enterprise.

According to economic historian Alan Milward, experience in the wartime economy of World War II and also detailed economic statistics introduced during the war helped regenerate the economy after the war and establish an international economic system with the Bretton Woods system, which replaced the international economic anarchy of the 1930s.

The USA gained its status as a superpower in the Second World War. Britain, on the other hand, had become dependent on borrowing and renting supplies from the USA. Already during the war, this led Britain to agree to the principle of free trade with the Atlantic Charter and to give up tariff and non-tariff trade preferences in favour of the Commonwealth states. Associated with the idea of free trade was the abandonment of bilateral trade treaties, trade blocs, import and export controls, and capital controls that had hampered world trade in the period between World War I and World War II, and the idealistic idea that free trade could prevent wars. Efforts culminated in 1947 with the conclusion of the General Agreement on Tariffs and Trade (GATT), under which participating nations agreed to phase out tariffs and other trade barriers.