Nonaggression pact
The USSR
soviet union
The Soviet Union
Germany wanted to ensure its military was free to invade Poland. The USSR, for its part, annexed the western side of Poland and the Baltic countries.
The Hitler/Stalin nonaggression pact was at the expense of Poland. Germany occupied western Poland and the USSR occupied eastern Poland, triggering WW II because Britain and France had promised to defend Poland.
Poland
The first two countries to go into WW2 were Nazi Germany and Poland prior to the invasion of Poland by Nazi Germany.
The German invasion of Poland... complements of THE DENNIS JONESGermany invading Polandthe German invasion of Poland
Poland
Mongol invasion of Poland happened in 1240.
The Invasion of Poland was from 1 September - 6 October 1939