Traditionally, you sort of had to take heavily defended positions in order to conquer territory because if you didn't, the defenders would cut of your supply li

Traditionally, you sort of had to take heavily defended positions in order to conquer territory because if you didn't, the defenders would cut of your supply lines and attack your rear. A key idea of Blitzkrieg (or "maneuver warfare" as it's called today) is that if you can move fast enough, this stops being true. You don't rely on fixed supply lines, and they can't attack your rear when they're not sure where you are and could be somewhere else by the time they organize an attack.