Phoney War

The period of relative inactivity on the Western Front from Britain and France’s declarations of war on Germany in September 1939 until Germany attacked in May 1940.

Sitzkrieg: A German nickname for the quiet Western Front during the early months of the Second World War. This near-synonym captured the contrast between declared war and limited fighting.
Invasion of Poland: Germany’s invasion of Poland on 1 September 1939, which began the Second World War in Europe. The invasion triggered Britain and France’s declarations of war on Germany.
Battle of France: Germany’s May–June 1940 campaign that defeated France and forced the evacuation of Allied forces from continental Europe. The German offensive ended the Phoney War and rapidly transformed the Western Front.
Blitzkrieg: A term for fast, concentrated military campaigns combining mobile forces and air power, associated with German victories early in the Second World War. Its rapid offensives contrast sharply with the slow, largely static Western Front before May 1940.
Maginot Line: A French system of fortifications built along part of the border with Germany before the Second World War. Its defensive logic encouraged France to await a German attack rather than advance far into Germany.
Anglo-Polish military alliance: The 1939 agreement in which Britain pledged support to Poland if it faced aggression. Britain’s commitment made the German invasion a cause for war.
Fall of France: The defeat of France by Germany in 1940 and the collapse of the French Third Republic. The long lull gave way to a campaign that removed France from the war as a major combatant.
Winter War: The war between the Soviet Union and Finland from November 1939 to March 1940. Major battles in Finland unfolded during months of limited fighting between France and Germany.
Saar Offensive: A French incursion into the Saar region of Germany in September 1939, followed by withdrawal. It was the principal French ground advance against Germany during the period.
French declaration of war on Germany: France’s declaration of war on Germany on 3 September 1939, following the invasion of Poland. It marked France’s formal entry into the war despite limited action on the Western Front.

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Neville ChamberlainBroader topic: Chamberlain remained prime minister during the opening months of the war, before its rapid expansion in 1940.