My understanding is that in WWI artillery and machine guns were so powerful that it led to it being advantageous for both sides to maintain defensive positions.However, by the time of WWII, tanks, aircraft, and infantry semi-automatic weapons made mobile warfare again practical and successful. There were situations in WWI where attempts to attack resulted in disproportionate casualties for the attackers, and that somewhat similar situations had occurred in the American Civil War, where the greater range and fire rate of artillery and small arms made some frontal assualts into disasters. Particularly, in the Battle of France the French tried to use a defensive approach, exemplified by the Maginot Line, whereas the Germans used an aggressive mobile approachs. Is this simplistic? Is my understanding correct?