The scale of the casua lties in World War II reflected not only the length and nature of the war. but also the weapons used. Land warfare involved few weapons that had not been used in World War I, but they had become much mo re deadly in the subsequent world war. TIle power and re liability of the internal combustion engine was greatly improved , makin g possible the introduction of swift and well-arm ed and armored tank s. A rtillery, as the war progressed , also became much more mob ile. By the end of the war , infantry had their own mechanized troopcarriers, which provided them with a degree of protection on the batt lefield and grea tly imp roved their mobilit y. In star k contrast to the mud-bound battl efields of 1914-1 8, World War II witnessed a re-emergence of movement on the batt lefield . And movem ent combined with firepower became the cornerstone of military success.