The extent of preparedness that each country had is widely different. Plan Barbarossa hit the Soviet Union, which was trying to remain neutral after the civil war busy rebuilding the country, very hard. Only in 43~ had the Soviet Union start producing what the army needed, before that the army was literally not capable to fight the Nazi Germany.

German Tanks, Planes, mortars, and etc. Were all an extreme threat to an army which was at the moment stuck with Mosins. Defense position were stormed with Blitzkrieg, and the majority infantry positions was not prepared for that.