If 3/4 of an army is either tanks or mechanized infantry, then you can still blitz.
Always make sure to have a balanced force (as one of the European powers + America). I was Germany facing off against a USSR player, and after 2 huge wars (in which he had nearly only infantry, but a rather large amount of it), the first of which was a draw, I managed to slice through his poorly placed infantry, and destroy half his army... and he was out of manpower... I raced across the countryside and defeated him. Had he had a armored force and an air force, things would have been much more difficult, maybe impossible. Infantry take up 20 manpower, while armor is only 1/2 that, and planes are 1/10 that.
Always make sure to have a balanced force (as one of the European powers + America). I was Germany facing off against a USSR player, and after 2 huge wars (in which he had nearly only infantry, but a rather large amount of it), the first of which was a draw, I managed to slice through his poorly placed infantry, and destroy half his army... and he was out of manpower... I raced across the countryside and defeated him. Had he had a armored force and an air force, things would have been much more difficult, maybe impossible. Infantry take up 20 manpower, while armor is only 1/2 that, and planes are 1/10 that.