Silly question: Almost everybody round the world may heard about hitler fascists invasion of USSR.
The "barbarossa" invasion army of german imperialism is considered the largest attack force in world history.
But the germans were NOT alone!
2/
Besides german imperialists eastern armies invading USSR from june 22, 1941 with an estimated staggering 3 million troops,
especially Finland and Romania flanked the german attack: Finland from north with 475.000+, Romania from south with up to 680.000 troops: alone in 1941!
3/
Finnish Republics aggression against USSR from june 25, 1941, jointly carried out with german fascists military help, was, among other things, essential for establishing the SIEGE OF LENINGRAD, one of the most atrocious war crimes in world history, with Finland participating.