German Invasion of Poland, 1939

Germany invaded Poland on 1 September 1939, combining armoured and air power with attacks across several frontiers. Britain and France declared war on Germany two days later. Soviet forces entered eastern Poland on 17 September under the terms of the Nazi–Soviet arrangements, and organised Polish resistance continued after the final major formations surrendered in early October.

For historical fiction, the campaign marks both a military catastrophe and the beginning of occupation, displacement and clandestine resistance. Stories can follow soldiers, civilians, diplomats, refugees and intelligence officers as state institutions collapse and are reconstructed underground.