World War II started when Germany invaded Poland on 1 September 1939.

Quick Scoop

  • The widely accepted start of World War II is Germany’s surprise attack on Poland, launched at dawn on 1 September 1939.
  • This invasion prompted Britain and France to declare war on Germany on 3 September 1939, turning a regional conflict into a global war.
  • The attack on Poland combined fast-moving ground forces and air power, a strategy later known as blitzkrieg (“lightning war”).

Extra context

  • The German invasion of Poland followed the Molotov–Ribbentrop Pact, a non‑aggression agreement between Germany and the Soviet Union that secretly planned to divide Eastern Europe.
  • On 17 September 1939, the Soviet Union also invaded Poland from the east, and by early October the country was fully occupied and partitioned.

Information gathered from public forums or data available on the internet and portrayed here.