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This Day in American History

September 1

1 historic event on this date

Historical1939

Germany Invades Poland; U.S. Neutrality Debate Intensifies

Germany invaded Poland, beginning World War II in Europe. President Roosevelt declared American neutrality but began working to revise the Neutrality Acts to allow arms sales to the Allies, sparking intense debate between interventionists and isolationists.

Why It Matters

The debate over American involvement in World War II tested fundamental questions about the nation's role in the world and the balance between democratic deliberation and executive leadership in national security.

Explore the Principles Behind the History

Every event in American history connects to the founding principles. Discover the ideas that shaped these moments.

View the 28 Founding Principles