German invasion of Poland – WWII begins

In 1939, on the 3rd of April, Hitler orders his generals to prepare for an invasion of Poland. The invasion will start on September the first of that year. Hitler has demanded that Poland gives back the coastal city of Danzig, now known as Gdansk, which used to be German. He also wants an access route - a corridor - to German East Prussia, here in northern Poland. Poland refuses.

They have been promised help from Britain if Hitler attacks. At the same time, Hitler and his generals are worried. If they invade Poland, that could provoke a Soviet attack on Germany. Hitler does not want a war in which they may have to fight against France and Britain in the west, and the Soviet Union in the east, a war on two fronts. In the Soviet Union, people are thinking the same thing.

They are being threatened by Japan in the East, and by Germany in the West. The Soviet leader, Josef Stalin, is trying to forge an alliance with Britain and France. That should be strong enough to stand up to the Nazis if they think of starting a war. Stalin’s requirement for setting up such an alliance is that the Soviet Union will take control of the Baltic and Eastern Poland. Exactly those areas that the Soviet Union lost after the First World War.

Britain and France refuse to agree to Stalin's requirement. In August 1939, Hitler now invites the communist Soviet Union to join an alliance with him. He has always hated communism, and has said that the Soviet Union is Germany's greatest enemy. Hitler's plan is to defeat his enemies France and Britain in the west, before attacking the Russians. But of course he doesn’t tell Stalin that. [...] Stalin, who has always said that Hitler and Germany are the greatest enemy of the Soviet Union, does not oppose an alliance.

Not right now. This gives Stalin time to take care of Japan in the east first. On the 23rd of August, Germany and the Soviet Union sign an agreement - a pact - promising not to attack each other. The pact is named after the Soviet and German Foreign Ministers Vyacheslav Molotov and Joachim von Ribbentrop, The Molotov - Ribbentrop Pact. The former deadly enemies are suddenly on the same side, they are allies.

September 1st at 4:45 am: Germany attacks Poland. Two days later, on September the 3rd, Britain and France declare war on Germany. The Second World War has begun.