In 1936 Hitler remilitarized the Rhineland. Hitler marched 22,000 troops in, in a direct defiance of the Treaty of Versailles.
March 1938, Hitler annexes Austria. Austria was in full support of the takover.
Hitler promised the British prime minister he wouldn't take anyone else over, But on September 1938 to March 1939, Hitler was preparing to annex Czechoslovakia. Czechoslovakia was expecting to be backed by France and Britain. But Britain didn't want war so they didn't.
In May of 1939, Italy and Germany agree to a political and military alliance. Mussolini called this a pact of steel.
On August 23, 1939 Hitler and Stalin sign the nonaggression act, in which each countries promise not to attack each other.
In September of 1939 1.5 Million German troops prepare to invade Poland! Naval forces attacked and air forces bombed Polish airfields. On September 3, Poland declared war on Germany. This started WW2.