World War II began with Germany invading which country?

Germany’s invasion of Poland on September 1 1939 triggered World War II prompting France and the UK to declare war. Russia Spain and the UK were not initial targets. This event marked the start of a global conflict reshaping international alliances. Understanding this invasion provides insight into the causes of World War II highlighting aggressive expansionist policies and their consequences. The invasion’s impact led to widespread geopolitical changes still studied for their historical significance. Update as of 2025-09-02 Poland’s role remains central in WWII historical analyses.