You’re thinking the Soviet Union was invaded in June 1941. Hitler had conquered Poland 2 years before. He invaded the USSR as he planned to all along, he wanted to weaken France and England before he focused on the Soviets. It was part of his conquest plans, plus by the non-aggression pact he avoided a two-front war that would have stretched his forces out.

Lebensraum was his excuse. He also had some vague notion that the Polish were Germanic due to the prevalence of blond, blue-eyed Poles. After the invasion he had many young, Polish children “relocated” to Germany to be adopted by fine, upstanding Germans - SS Officers and high Party officials in particular.
The invasion was September 1st, 1939.
I think you’re thinking of his invasion of the Soviet Union which violated the non-aggression pact he signed with Stalin. In this event, he was seeking the raw materials Russia had to offer, the oil reserves in the Caucasus in particular, as well as his notion that he was a modern day Napoleon. His army met the same end.
Basically, Hitler thought he had the right to due anything.
How’d he make out?

Reunification with East Prussia, ‘living space’ for the German folk, and first step in the elimination of the Bolsheviks….(after doing away with the Poles first)….

Liebenstant….”Living space”. Of course i realize that the German word is spelled wrong so hopefully someone will correct that.
The name of the game was to expand to make the Reich all encompassing and swallow up any and all resources the country had.
After that came the elimination of Jews, Gypsies, Catholics, Homosexuals, Political Dissidents and anyone else who was considered an ‘enemy of the state”.