Weaknesses did hamper operations, notably the poor state of naval aviation, particularly when compared with naval aviation in the United States and Japan. Of the seven aircraft carriers in service at the start of 1939, only the Ark Royal (laid down in 1935) could be considered a modern carrier. Four of the other six had been modified earlier from battleship or battle cruiser hulls. The five new fleet carriers under construction would not begin operational service until well into 1940.
Despite the lessons of antisubmarine warfare (ASW) learned by 1918 and the need to protect merchant shipping and convoys, the Royal Navy had relatively poor commerce protection capabilities in 1939. Warship design had primarily emphasized coastal protection and submarine hunting, resulting in the short-range corvette ship type, which first came into service in 1939, and small escort destroyers. Although these ships had long-endurance capabilities, they proved unsuitable for open-ocean convoy escort primarily because of their size. Open-ocean convoy protection had been neglected, especially in training programs, and larger destroyers capable of trans-Atlantic convoy protection were in short supply. Despite the drawbacks, Britain managed to improve ASW capability and assets fairly quickly in response to the German U-boat threat. Although the smaller corvettes proved minimally effective for long-range mid-ocean operations, their successor—the larger, more seaworthy frigate, particularly the River-class dating from the 1940 building program—proved especially effective for convoy escort after 1942.
The initial German threat came from a three-part German offensive against commerce ( Handelskreig) based on submarines, mines, and surface raiders. The Royal Navy quickly and effectively addressed each threat, although significant casualties did occur. Germany began the war with not many more submarines than it had at the start of World War I—just 51 operational U-boats, about half of them coastal vessels. The organization of British convoys in the Western Approaches, combined with the Straits of Dover mine barrage, resulted in nine U-boats sunk by the end of 1939.
Although some vessels were lost to German mines, the navy reduced this menace with new technology, including degaussing against magnetic mines. Surface raiders threatened British commerce, particularly in the remote waters of the Indian Ocean and South Atlantic. Although Germans raiders such as the Atlantis and pocket battleship Graf Spee provided some tense moments early in the war, by late 1941 most surface raiders had been hunted down and sunk.
In April 1940, Germany attacked Norway, primarily to secure its northern flank and the vital iron ore trade with Sweden. The British navy opposed the German landings, but a daring run of 10 German destroyers into Narvik subdued the Norwegian defenses. The combination of the entire German surface fleet with German land-based air power quickly resulted in the occupation of Norway. Reacting to the German moves, a Royal Navy force of destroyers attacked the Germans at Narvik, but it suffered heavy losses. A follow-on attack three days later by a large force based around the battleship Warspite devastated the Germans, which severely hampered future enemy surface operations. Ultimately, though, the Royal Navy could not prevent German victory, especially in the face of effective enemy airpower. Additionally, the German fast battleships Scharnhorst and Gneisenau sank the fleet carrier Glorious.
The fall of France and loss of French ports heralded a realignment of Royal Navy forces, because prior to World War I, Britain had relied on France for the bulk of Mediterranean sea power. With the appearance of a hostile Vichy government, though, the navy established Force H based at Gibraltar under Vice Admiral Sir James Somerville and charged with controlling the western Mediterranean. Force H carried out a distasteful duty in the bombardment of the French Fleet at Mers-el-Kébir in July 1940. Force H also played a central role in the destruction of the German battleship Bismarck in May 1941, as well as in hunting down and destroying the Atlantic commerce raiders. But the loss of France allowed Germany to base long-range U-boats in Bay of Biscay ports such as Brest and Lorient. The toll on British and Imperial shipping dramatically increased by autumn 1940 as Adolf Hitler declared (on 17 August 1940) a total blockade of the British Isles.
By autumn 1941, the tide in the commerce war had turned in favor of Britain. Escort ships provided by the United States (50 World War I–era destroyers) and the increasing number of Royal Canadian Navy destroyers, improved detection equipment including radar; high-frequency direction-finding sets and Antisubmarine Detection Investigation Committee (ASDIC or sonar), implementation of a cohesive and effective enemy submarine tracking system based on radio intercepts and code-breaking, and better cooperation with RAF Coastal Command all contributed to the reduction of the German submarine threat and effectiveness. Additionally, Germany's loss of the Bismarck and the relatively ineffective German effort to use heavy surface units to interdict the convoys to the northern Soviet Union across the Arctic above Norway all helped to lessen the threat to British maritime commerce by the middle of 1943. The Soviet convoys began receiving more robust escort following the destruction of the ill-fated PQ17 convoy in summer 1942. This enhanced escort included greater destroyer strength and escort carriers. The destruction of the battleship Scharnhorst off the Norwegian North Cape in December 1943 by a British battleship and cruiser force essentially ended the German surface threat to British and Allied maritime shipping.
Finally, despite a high number of U-boats operating in the Atlantic by March 1943 (up to 70 at any given time), the increasing skill of Allied submarine hunters and the closing of the "Black Hole" area south of Greenland, where air cover had not been previously available, meant a diminishing submarine threat and higher losses in U-boats. Escort carriers provided air cover while long-range maritime patrol aircraft (primarily modified B-24 Liberator bombers) made U-boat operations less effective. Additionally, hunter-killer escort groups attached to vulnerable convoys mauled the Germans.
In the Mediterranean, Italy's entry into the war in May 1940 required reinforcement of the theater naval forces under Admiral Sir Andrew Cunningham. With some modernized older battleships and the new carrier Illustrious, Cunningham defeated the Italians in fleet engagements at Calabria in July 1940 and Cape Matapan in March 1941 and raided the Italian anchorage at Taranto in November 1941 with naval aircraft. Cunningham stressed the improvement of antiaircraft protection, which paid off as the naval war in the Mediterranean increasingly devolved into attacks on shipping and naval vessels by Axis aircraft.
Faced with substantial damage to their supply convoys by British destroyers and submarines, the Germans dispatched U-boats to the Mediterranean in October 1941, resulting in the sinking of the battleship Barham and the carrier Ark Royal. At the fleet anchorage in Alexandria, the battleships Queen Elizabeth and Valiant were sunk at their moorings by Italian Maiale human torpedoes.
Faced with the loss of capital ships and the threat of enemy aircraft and submarine attack, British resources in the Mediterranean were stretched dangerously thin. Malta, the linchpin of Britain's efforts to hold the Mediterranean, came under horrendous air attack. Convoys to resupply and reinforce the island suffered substantial casualties, among them the aircraft carrier Eagle.
The entry of the United States into the war in December 1941 had a profound impact on the Mediterranean Theater. Operation torch, the Allied landings in North Africa in November 1942, resulted in the eventual destruction of Axis forces in North Africa. Reinforced and reconstituted, the Mediterranean Fleet conducted an ambitious and destructive assault on Italian shipping throughout 1942 and 1943 that crippled enemy resupply efforts. Cunningham admonished his sailors and airmen to "sink, burn and destroy: let nothing pass." By the end of 1942, Britain had again established maritime supremacy in the Mediterranean, despite substantial losses.
In the Pacific Theater, Japan entered the war against Britain concurrent with the assault on the United States. Quickly overrunning Hong Kong, the Japanese army forced the capitulation of Singapore, Britain's "Gibraltar of the Pacific." Faced with the loss of basing facilities, the Royal Navy withdrew from Southeast Asian waters, particularly after the loss of the battleship Prince of Wales and battle cruiser Repulse to air attack in December 1941 (Force Z under Admiral Sir Tom Phillips). The admiral's disregard of the air threat coupled with woefully inadequate antiaircraft protection (the navy had only two modern destroyers) greatly aided the land-based Japanese aviators, who easily sank both capital ships.
Following the crippling of the U.S. Pacific Fleet at Pearl Harbor, Japan's main striking force—Vice Admiral Nagumo Chuichi's First Air Fleet—wreaked havoc on the remnants of British sea power in the Indian Ocean in spring 1942. In carrier-based air attacks against British surface units, the veteran Japanese naval aviators sank detached portions of Admiral Sir James Somerville's forces based in Ceylon, including two cruisers and the carrier Hermes. However, Somerville avoided a general action and preserved his force as the Japanese withdrew to support their thrust into New Guinea and the Solomon Islands. Naval action in the Pacific Theater after May 1942 involved mainly U.S. and Australian naval units, but, with the defeat of Germany in May 1945, the Royal Navy again engaged Japan with substantial forces.
Under Admiral Sir Bruce Fraser, the Pacific Fleet of four carriers (later joined by two additional decks) and two battleships with substantial escort destroyers and cruisers arrived in the Pacific in March 1945, where they joined the Americans in the assault on the Japanese home islands and Okinawa. Equipped with the U.S. Hellcat and Corsair fighters, Royal Naval aviators did great destruction to the Japanese. American aircraft proved greatly superior to earlier British Seafire (modified from the Spitfire), Martlet, Fulmar, and Sea Hurricane models. The heavily armored British carrier decks proved worthwhile as a defense against Japanese suicide kamikaze aircraft (the lightly armored American carriers suffered more extensive damage).
From strategic and operational viewpoints, the Royal Navy performed exceptionally well in the war. Although losses were heavy (1,525 warships of all types, including 224 major surface units of which 5 were battleships or battle cruisers and 5 were fleet carriers; and 50,000 personnel dead), the aggressiveness and risk-taking nature of senior and individual ship commanding officers overcame the tenacious and highly competent Axis opponents. In the Atlantic, the Axis commerce warfare offensive failed to starve the country into submission or impede the arrival of overwhelming U.S. forces and personnel. In the Mediterranean, the Royal Navy kept British and Imperial ground and air forces supplied and reinforced while simultaneously strangling the Axis supply lines to North Africa. In the Pacific, despite initial defeats by the Japanese, British sea power returned late in the conflict and helped the U.S. Navy carry the fight to the Japanese home islands. As it had not done in the previous war, the navy at all levels showed exceptional ability to adapt rapidly to technological and methodical innovations and advances in doctrine, organization, and training. To man the new ships of more than 900 major combatants and the supporting shore establishment (training, research, logistics, support, and administration), by war's end Royal Naval personnel had increased from the prewar 129,000 to 863,500, which included 72,000 women in the Women's Royal Naval Service (WRNS). In short, the navy vindicated itself following the disappointments of World War I. British sea power both kept Britain in the fight until the United States arrived in force and subsequently provided the domination needed to attack the Axis powers at all vulnerable points with little interference. Stanley D. M. Carpenter
Barnett, Correlli. Engage the Enemy More Closely: The Royal Navy in the Second World War. New York: W. W. Norton, 1991.; Gray, Edwyn. Operation Pacific: The Royal Navy's War against Japan, 1941–1945. London: Cooper, 1990.; Jackson, Robert. The Royal Navy in World War II. Annapolis, MD: Naval Institute Press, 1997.; Roskill, Stephen W. The War at Sea, 1939–1945. 4 vols. London: Her Majesty's Stationery Office, 1954–61.; Roskill, Stephen W. White Ensign: The British Navy at War, 1939–1945. Annapolis, MD: Naval Institute Press, 1991.; Titterton, G. A. The Royal Navy and the Mediterranean. Vol. 1. London: Whitehall History in association with Frank Cass, 2002.
Stanley D. M. Carpenter