Territory held by Germany and its allies in mid-1941 during the Second World War

By mid-1941, Axis forces had already taken control of most of mainland Europe, as well as much of Northern Africa and parts of the Middle East*. At the outbreak of Operation Barbarossa, the major European countries not under Axis control were the officially-neutral states of Ireland, Portugal, Spain, Sweden, Switzerland, and Turkey, while the Soviet Union and United Kingdom were actively at war with the Axis Powers. By mid-1941, Germany and its allies controlled an area of approximately 3.28 million square kilometers in Europe; by comparison, modern Germany covers an area of approximately 357 thousand square kilometers.

Axis control of Europe

From September 1938, when Germany annexed the Czech Sudetenland, until June 1941, when Germany launched its invasion of the Soviet Union, the Axis Powers spent much of their time and resources consolidating power across Europe. Countries such as Bulgaria, Hungary, Romania, and Finland aligned themselves with Germany, as did Italy, who became one of the chief aggressors around the Mediterranean and in Africa. Germany and the Soviet Union both invaded and partitioned Poland in September 1939, through the Molotov-Ribbentrop Pact of non-aggression to one-another. Germany then took Denmark and most of Norway in April 1940, before pushing into Benelux and France in May. Italy also annexed Albania in April, which was used as a launching point for its failed invasion of Greece later in the year. As Italy had failed to secure the Balkans, a joint Axis offensive then pushed into Yugoslavia and Greece in April 1941, ultimately overwhelming any resistance. However, German intervention in the south then delayed the Axis invasion of the Soviet Union by over a month; Hitler later claimed that this was the reason for Germany's failure to take Moscow before the winter months, although many historians disagree.

Launch of Operation Barbarossa

Germany broke their pact of non-aggression with the Soviet Union with a surprise invasion, known as Operation Barbarossa, on June 22, 1941. While Axis forces had already extended control over most of Europe by this point, Operation Barbarossa became the largest military invasion or operation in human history. When compared with German capacities in its pre-1938 borders, within a few months of the invasion, the area of land controlled by Germany had grown by a factor of six, the population by a factor of four, and its access to natural resources and energy had also grown several times larger. These increased capacities were essential in allowing Germany to continue its expansion and aggression for the years to come, before the Soviet Union and the Western Allies eventually defeated the Axis forces four years later.