Final steps to war

Munich Agreement (1938)

The Munich Agreement was a settlement permitting Nazi Germany’s annexation of portions of Czechoslovakia along the country’s borders.
Signed by Germany, Italy, the United Kingdom, and France, it became a symbol of appeasement, the diplomatic policy of making political/military concessions to an aggressive power to avoid conflict.
British Prime Minister Neville Chamberlain praised the agreement as achieving “peace for our time”, but it was heavily criticised, most notably by Winston Churchill.
The Munich Agreement became void in March 1939 when Hitler violated the agreement by invading Czechoslovakia.

Nazi-Soviet Pact (1939)

The Nazi-Soviet Pact was a non-aggression pact between Germany and the Soviet Union that enabled those two powers to divide-up Poland between them.
Its formal name was the Molotov-Ribbentrop Pact and it was signed in Moscow on 23 August 1939.
It also contained a secret protocol dividing the states of Northern and Eastern Europe into German and Soviet spheres of influence.
The pact was broken when Nazi Germany attacked the Soviet Union less than two years later in June 1941.

Invasion of Poland and the Outbreak of War (1939)

The Invasion of Poland, also known as the September Campaign or 1939 Defensive War in Poland, marked the beginning of World War II.
The German invasion began on 1 September 1939 following the signing of the Nazi-Soviet Pact, while the Soviet invasion commenced on 17 September following the Molotov-Tōgō agreement that terminated the Russian and Japanese hostilities in the east on 16 September.
The Polish army was defeated within weeks of the invasion.
As a result, Britain and France declared war on Germany, marking the start of World War II. This represented the end of appeasement and the beginning of Allied opposition to Nazi aggression.
Despite the declaration of war, Britain and France could provide little direct support for Poland.