The pact reduced the immediate risk of Soviet opposition to Germany. The invasion of Poland began the fighting; British and French declarations widened the war.
The Soviet Union was a communist state led by Joseph Stalin. It and Nazi Germany were political enemies, yet on 23 August 1939 they made a non-aggression pact, promising not to attack each other. For Hitler, this reduced the risk of Soviet military opposition if an attack on Poland also brought war with Britain and France. Stalin sought time, security and territorial opportunities after talks with the Western powers failed to produce an agreement. Each side saw an advantage in a bargain with an enemy.
A secret protocol, an additional part of the agreement, divided spheres of influence in eastern Europe: areas each power claimed the right to dominate. It anticipated territorial changes affecting Poland. The public promise of peace between Germany and the Soviet Union therefore went alongside a private bargain at their neighbours' expense. It did not mean their political beliefs had become the same or that either had promised to leave Poland alone.
Germany invaded Poland on 1 September 1939. Britain and France had committed themselves to Polish security. After Germany failed to meet their demands to withdraw, they declared war on 3 September. Soviet troops invaded eastern Poland on 17 September. Keep these roles distinct: the pact made an attack less risky for Hitler; the invasion began the fighting; British and French decisions brought them into the war. The pact did not itself declare war or make the invasion automatic.
Worked example: Connect the pact, attack and declarations
Why did an agreement signed in August matter to the war that began in September?
- The Soviet promise not to attack reduced an obstacle in Hitler's calculations: the risk of facing Soviet opposition while also risking war with Britain and France.
- Hitler then chose to invade Poland on 1 September. That decision turned a crisis into fighting.
- Britain and France declared war on 3 September after Germany failed to withdraw. An agreement that made aggression easier and the actions that began and widened war did different jobs in the explanation.
Watch out for this
Signing the Nazi-Soviet Pact was the act that started the war in Europe.
The pact reduced a risk for Hitler, but fighting began with the German invasion of Poland on 1 September. Britain and France declared war two days later.
Check your understanding
Which sequence is correct?
- British declaration, German invasion of Poland, Nazi-Soviet Pact.
- German invasion of Poland, pact, Soviet invasion of Poland.
- Nazi-Soviet Pact, German invasion of Poland, British and French declarations, Soviet invasion of eastern Poland.