World War II: The Navy

Naval power was central to the Second World War, determining control of vital sea routes and enabling or denying the movement of armies and supplies across the globe. The world's navies fielded a wide range of warship types, each designed for a particular role, and the war saw a major shift in the balance between traditional surface fleets and newer forms of sea power.

The largest gunned warships were battleships and battlecruisers, heavily armoured vessels carrying the biggest naval guns; famous examples include the German Bismarck and Scharnhorst. Cruisers and destroyers provided escort, scouting and fire support, while torpedo boats operated in coastal waters. The war confirmed the rise of the aircraft carrier, whose embarked aircraft could strike targets far beyond gun range; carrier aviation proved decisive in several Pacific battles. Smaller escort carriers were built in large numbers to protect convoys.

Beneath the surface, submarines transformed naval warfare. German U-boats waged a prolonged campaign against Allied merchant shipping in the Battle of the Atlantic, attacking convoys with torpedoes and threatening Britain's supply lines, while surface raiders sought to disrupt commerce on the open ocean. The Allied response combined convoy escorts, long-range aircraft, improved sonar and codebreaking. By the war's end, the eclipse of the battleship by the carrier and the submarine marked a lasting change in naval strategy.

Frequently asked questions

Why did aircraft carriers become so important?

Carriers could launch aircraft to attack ships and shore targets far beyond the range of naval guns, allowing fleets to strike first and at great distance, as shown in several Pacific battles.

What was the Battle of the Atlantic?

It was the long campaign in which German U-boats attacked Allied shipping in the Atlantic, countered by convoys, escort warships, aircraft and improved detection methods.

What was the difference between a cruiser and a destroyer?

Cruisers were larger, more heavily armed warships for independent or fleet operations; destroyers were smaller, faster vessels used mainly for escort, anti-submarine work and torpedo attacks.