Pursuant to the Munich Agreement signed the day before, Nazi Germany begins the military occupation and annexation of Czechoslovakia's Sudetenland.

The Munich Agreement was reached in Munich on 30 September 1938, by Nazi Germany, the United Kingdom, France, and Italy. The agreement provided for the German annexation of part of Czechoslovakia called the Sudetenland, where three million people, mainly ethnic Germans, lived. The pact is known in some areas as the Munich Betrayal, because of a previous 1924 alliance agreement and a 1925 military pact between France and the Czechoslovak Republic.

Nazi Germany, officially the German Reich and later the Greater German Reich, was the German state between 1933 and 1945, when Adolf Hitler and the Nazi Party controlled the country, transforming it into a totalitarian dictatorship. The Third Reich, meaning "Third Realm" or "Third Empire", referred to the Nazi claim that Nazi Germany was the successor to the earlier Holy Roman Empire (800–1806) and German Empire (1871–1918). The Third Reich, which the Nazis referred to as the Thousand-Year Reich, ended in May 1945, after 12 years, when the Allies defeated Germany and entered the capital, Berlin, ending World War II in Europe.

Czechoslovakia was a landlocked country in Central Europe, created in 1918, when it declared its independence from Austria-Hungary. In 1938, after the Munich Agreement, the Sudetenland became part of Nazi Germany, while the country lost further territories to Hungary and Poland. Between 1939 and 1945, the state ceased to exist, as Slovakia proclaimed its independence and Carpathian Ruthenia became part of Hungary, while the German Protectorate of Bohemia and Moravia was proclaimed in the remainder of the Czech Lands. In 1939, after the outbreak of World War II, former Czechoslovak President Edvard Beneš formed a government-in-exile and sought recognition from the Allies.

The Sudetenland is a German name for the northern, southern, and western areas of former Czechoslovakia which were inhabited primarily by Sudeten Germans. These German speakers had predominated in the border districts of Bohemia, Moravia, and Czech Silesia since the Middle Ages.