Having the best troops and equipment is important but does not guarantee victory. You need to be able to win a battle but also hold the ground, constantly supply the forces, rotate the troops, manufacture the guns bullets, ships, trucks, tanks, and aircraft. You need to constantly research new weapons as the enemy finds countermeasures. You need to keep the homeland economy running and manage the money. Hitler underestimated his foes, stretched his forces thin. He overestimated his nation's industrial might maybe not considering his limited natural resources and the impact round the clock carpet bombing would have on trying to keep factories running.