Areas annexed by Nazi Germany in the context of "Alsace-Lorraine"

The Flensburg Government (German: Flensburger Regierung), also known as the Flensburg Cabinet (Flensburger Kabinett), the Dönitz Government (Regierung Dönitz), or the Schwerin von Krosigk Cabinet (Kabinett Schwerin von Krosigk), was the rump government of Nazi Germany during a period of three weeks around the end of World War II in Europe. The government was formed following the suicide of Adolf Hitler on 30 April 1945 during the Battle of Berlin. It was headed by Grand Admiral Karl Dönitz as Reichspräsident and Lutz Graf Schwerin von Krosigk as the Leading Minister. The administration was referred to as the "Flensburg Government" because Dönitz's command relocated to Flensburg in northern Germany near the Danish border on 3 May 1945. The sports school at the Mürwik Naval School was used as the government headquarters. The cabinet was not legitimised according to the Weimar Constitution, which was still formally in force.

At the time of its formation, forces loyal to the Nazi regime still held control of most of Austria and the Sudetenland, which was annexed by Germany in 1938. They also still controlled most of the Protectorate of Bohemia and Moravia which was partially annexed in 1939 when the remainder of Czechoslovakia was occupied, although after Hitler's death those Czech lands still occupied were effectively controlled by the SS with little meaningful oversight from Flensburg. Furthermore, the German military continued to occupy other non-German-speaking territories in disparate and isolated locations across Europe, such as Denmark, Norway, parts of the Netherlands, the Atlantic pockets in France and the British Channel Islands. However, in addition to losing most of its wartime conquests by this point, German forces had already been driven out of the vast majority of Germany's post-Anschluss territory, in addition to Luxembourg as well as the Polish and French territories Germany had either annexed or placed under direct German administration in the early stages of the war.

Following the Invasion of Poland at the beginning of World War II, nearly a quarter of the entire territory of the Second Polish Republic was annexed by Nazi Germany and placed directly under the German civil administration. The rest of Nazi-occupied Poland was renamed as the General Government district. The annexation was part of the "fourth partition of Poland" by Nazi Germany and the Soviet Union, outlined months before the invasion, in the Molotov–Ribbentrop Pact.

Some smaller territories were incorporated directly into the existing Gaue East Prussia and Silesia, while the bulk of the land was used to create new Reichsgaue Danzig-West Prussia and Wartheland. Of those, Reichsgau Wartheland was the largest and the only one comprising solely the annexed territory.

The Greater Germanic Reich (German: Großgermanisches Reich), fully styled the Greater Germanic Reich of the German Nation (German: Großgermanisches Reich der Deutschen Nation), was the official state name of the political entity that Nazi Germany tried to establish in Europe during World War II. The territorial claims for the Greater Germanic Reich fluctuated over time. As early as the autumn of 1933, Adolf Hitler envisioned annexing such territories as Bohemia, western Poland, and Austria to Germany and the formation of satellite or puppet states without independent economies or policies of their own.

This pan-Germanic Empire was expected to assimilate practically all of Germanic Europe into an enormously expanded Reich. Territorially speaking, this encompassed the already-enlarged German Reich itself (consisting of pre-1938 Germany proper, Austria, Bohemia, Moravia, Czech Silesia, Alsace-Lorraine, Eupen-Malmedy, Memel, Lower Styria, Upper Carniola, Southern Carinthia, Danzig, and Poland), the Netherlands, Belgium, Luxembourg, Denmark, Norway, Sweden, Iceland, Liechtenstein, parts of northern and northeastern France, and the German-speaking and French-speaking parts of Switzerland.

A Reichsgau (plural Reichsgaue) was an administrative subdivision created in a number of areas annexed by Nazi Germany between 1938 and 1945.