The Battle of Westerplatte was one of the first battles in Germany's invasion of Poland, marking the start of World War II in Europe. Beginning on 1 September 1939, German army, naval and air forces and Danzig police assaulted Poland's Military Transit Depot (Wojskowa Składnica Tranzytowa, or WST) on the Westerplatte peninsula in the harbor of the Free City of Danzig. The Poles held out for seven days and repelled 13 assaults that included dive-bomber attacks and naval shelling.

Westerplatte's defense served as an inspiration for the Polish Army and people in the face of German advances elsewhere, and is still regarded as a symbol of resistance in modern Poland.