 For this reason, the US Army believed that the M4 would be adequate to win the war, and relatively little pressure was initially exerted for further tank development.Logistical and transport restrictions, such as limitations imposed by roads, ports, and bridges, also complicated the introduction of a more capable but heavier tank.Tank destroyer battalions using vehicles built on the M4 hull and chassis, but with open-topped turrets and more potent high-velocity guns, also entered widespread use in the Allied armies.