<P> Advances were made in nearly every aspect of naval warfare, most notably with aircraft carriers and submarines . Although aeronautical warfare had relatively little success at the start of the war, actions at Taranto, Pearl Harbor, and the Coral Sea established the carrier as the dominant capital ship in place of the battleship . </P> <P> In the Atlantic, escort carriers proved to be a vital part of Allied convoys, increasing the effective protection radius and helping to close the Mid-Atlantic gap . Carriers were also more economical than battleships because of the relatively low cost of aircraft and their not requiring to be as heavily armoured . Submarines, which had proved to be an effective weapon during the First World War, were anticipated by all sides to be important in the second . The British focused development on anti-submarine weaponry and tactics, such as sonar and convoys, while Germany focused on improving its offensive capability, with designs such as the Type VII submarine and wolfpack tactics . Gradually, improving Allied technologies such as the Leigh light, hedgehog, squid, and homing torpedoes proved victorious . </P> <P> Land warfare changed from the static front lines of World War I to increased mobility and combined arms . The tank, which had been used predominantly for infantry support in the First World War, had evolved into the primary weapon . In the late 1930s, tank design was considerably more advanced than it had been during World War I, and advances continued throughout the war with increases in speed, armour and firepower . </P> <P> At the start of the war, most commanders thought enemy tanks should be met by tanks with superior specifications . This idea was challenged by the poor performance of the relatively light early tank guns against armour, and German doctrine of avoiding tank - versus - tank combat . This, along with Germany's use of combined arms, were among the key elements of their highly successful blitzkrieg tactics across Poland and France . Many means of destroying tanks, including indirect artillery, anti-tank guns (both towed and self - propelled), mines, short - ranged infantry antitank weapons, and other tanks were used . Even with large - scale mechanisation, infantry remained the backbone of all forces, and throughout the war, most infantry were equipped similarly to World War I . </P>

Where did world war 2 start and end