World War II was the first war where naval aviation took a major part in the hostilities. Aircraft carriers were used from the start of the war in Europe looking for German merchant raiders and escorting convoys. Offensive operations began with the Norwegian campaign where British carriers supported the fighting on land.
Carriers were important to the Mediterranean and Middle East theatre where they were used to resupply Malta's aircraft and so keep it viable in preventing resupply of Axis forces in North Africa.
Later in the war small escort carriers built on civilian cargo hulls took over convoy protection.
Naval historians such as Evan Mawdsley, Richard Overy, and Craig Symonds concluded that World War II's decisive victories on land could not have been won without decisive victories at sea.Mawdsley 2019 p478Overy, p. 61Symonds, p. 641 Naval battles to keep shipping lanes open for combatant's movement of troops, guns, ammunition, tanks, warships, aircraft, raw materials, and food largely determined the outcome of land battles. Without the Allied victory in keeping shipping lanes open during the Battle of the Atlantic, Britain could not have fed her people or withstood Axis offensives in Europe and North Africa.Overy 1995, pp18–19 Without Britain's survival and without Allied shipments of food, materiel and industrial equipment to the Soviet Union, her military and economic power would likely not have rebounded in time for Russian soldiers to prevail at Stalingrad and Kursk.Overy pp. 19, 254, 321
Allied operations in the Atlantic and Pacific war theaters were interconnected because they frequently competed for scarce naval resources for everything from aircraft carriers to transports and landing craft.Symonds, WWII at Sea, pp. xi–xii Effective transport of troops and military supplies between the two war theaters required naval protection for shipping routes around the Cape of Good Hope, through the Suez canal, and through the Panama Canal. In both theaters, maritime dominance enabled combatants to use the sea for their own purposes and deprive its use by adversaries. As naval historian Admiral Herbert Richmond stated, "Sea power did not win the war itself: it enabled the war to be won".Mawdsley, pp. xxxix, 477
Aircraft carriers played a major role in winning decisive naval battles,Symonds, p. 268 supporting key amphibious landings, and keeping critical merchant shipping lanes open for transporting military personnel and their equipment to land battle zones.
Atlantic war overview (1939-1945)
During the 1930s, Germany began rebuilding her military from its dissolution following World War I. She initially achieved annexations short of war by unopposed initiatives in Alsace-Lorraine, Austria, and Czechoslovakia. Germany launched the war in Europe with the invasion of Poland prompting war with Britain and France and the naval blockade of Germany. In 1940 Germany invaded Denmark and Norway, and then the Netherlands, Belgium, and France. Italy joined what she perceived would be a short war in order for her to benefit from the spoils. Although Britain was not invaded or subjugated by Germany's intensive bombing campaign, Britain's survival was threatened by an Axis blockade using submarines, warship raiders, and land-based aircraft that undermined her means to continue resisting. In North Africa Italy attempted an invasion of Egypt but was beaten back drawing Germany into the conflict there.
Germany boldly attacked the Soviet Union, initially with considerable success. Stiff resistance and the onset of bitter winter weather prevented a quick German victory, leading to protracted war on Germany's Eastern Front.
Prior to Japan's attack on Pearl Harbor that resulted in the United States formally entering the war in both the Pacific and Atlantic theaters, support for the war had been mixed with some noted industrialists (such as the Ford Motor company) providing material support to the Axis, while other elements supported the Allies. The attack on Pearl Harbor galvanized national support for the Allied nations and spurred the entrance of the United States into the war on the side of the Allies in both the Pacific and Atlantic theaters. Within a year, led by Soviet victory at Stalingrad, the British victory at the Second Battle of El Alamein, and the American stand at Guadalcanal, the tide of war began to turn against the Axis. Allied protection of convoys improved, permitting significant transportation of troops, equipment, and food to European war zones. The Allies moved toward Germany from the west by invading North Africa, then Italy, and then France. From the east, in the world's largest land battles, Russia confronted and drove back what was the bulk of Germany's huge army, ultimately overrunning Berlin.Overy, p. 19 Germany surrendered.
Carriers in the Atlantic theater (1939-1945)
From 1918, British naval aviation was within the Royal Air Force. The development of naval aircraft for the Fleet Air Arm was neglected as part of general limitations on military spending, and Britain's previous lead in naval air capability was lost. Naval aviation was returned to the control of the Admiralty in mid-1939.Mawdsley, p. 17-20Roskill, p.27-28 Coastal patrol remained with RAF. When war broke out in Europe in 1939, the Royal Navy had only about 400 aircraft compared to the US Navy with over 2,000.Mawdsley, p. 18 In the years leading up to the war, the majority of investment in UK was in building up the defensive fighter force. Throughout the war, British naval air competed with RAF Bomber Command for resources, and the strategic bombing campaign against Germany with long-range, land-based bombers typically had priority.
In 1939, the British navy had strong bases at both ends of the Mediterranean Sea, one at Alexandria, Egypt, and another at Gibraltar and a strong position in the central Mediterranean with Malta. The French Navy had strong naval bases at Toulon southern France and Mers-el-Kébir French Algeria from which it could exert great influence in Western Mediterranean. Located in the central Mediterranean and with land projecting well into the center of what they considered "mare nostrum" ("our sea"), the Italians relied upon surface vessels and land-based aircraft to dominate the Central Mediterranean. They did not perceive that they needed aircraft carriers.Mawdsley, p. 115-117
As part of the largest fleet in the world, Britain had seven aircraft carriers at the time of the declaration of war with Germany on 3 September 1939. and another five (of six planned) under construction. These carriers soon proved vulnerable to submarines, battleships, and land-based aircraft. Carriers had played no material role in World War I,Whitehouse, p. 30-31, and there were no battle-tested policies or procedures on how to use or protect them. Losses during their initial operations would provide sobering learning experiences. These losses resulted from questionable command decisions coupled with task assignments for which the carriers were not well suited or adequately protected.
Two weeks after the war began HMS Courageous was on an anti-submarine patrol with only a small screening force.Roskill 1960 p. 41 It was sunk by the German submarine U-29 off the coast of Ireland. HMS Ark Royal might well have been sunk the same week by U-39 if the U-boat's torpedoes had not been spottedRossiter, Mike (2007) . Ark Royal: The Life, Death and Rediscovery of the Legendary Second World War Aircraft Carrier (2nd edition). London: Corgi Books. ISBN 978-0-552-15369-0. OCLC 81453068. pp 74-77 Thereafter, such carriers were regarded by the Admiralty as too vulnerable to be used for anti-submarine patrols.Whitehouse p. 52 Eight months later, HMS Glorious was evacuating aircraft during the British withdrawal from Norway. Travelling independently it was discovered by two German battleships. With only two destroyers, aircraft landed and her own 4-inch guns to protect herself, she was sunk by the battleships' shellfire;Whitehouse p. 48 the first aircraft carrier to be sunk by gunfire. Her commander had not launched bombers to protect her from such warships, perhaps in part because of inability to sustain an effective launch and recovery cycle with her decks crowded with fighters recovered from Norway airfields that she was transporting back to Britain.Symonds, WWII At Sea, pp. 59–60 Even if aircraft had been deployed, however, the outcome may have been the same. British torpedoes, like those used by Germany and America at the time, were defective and often detonated prematurely or did not detonate at all.Whitehouse pp. 46, 67, 84Symonds, WWII At Sea, pp. 17, 53 Similarly, British anti-submarine bombs aboard Glorious at the time had almost no destructive powerOvery, p. 50
At the beginning of 1942, the USN Atlantic Fleet had, in Carrier Division 3, the three fleet carriers Ranger, Hornet, and Wasp and the escort carrier Long Island.
Over the course of the war, Allied carriers became increasingly effective. Aircraft from British and American carriers in the Atlantic Theater were used for both offensive and defensive operations. These included providing air cover during invasions; raiding enemy installations; blockading ports; patrolling for and attacking submarines, raiders, and land-based aircraft; protecting trade routes and convoys; and transporting aircraft, troops, and supplies for military and civilian use.Whitehouse p. 46 As America's shipbuilding capability was mobilized, large numbers of carriers became available to perform these tasks.
Carrier operations in the Pacific Theater tend to receive more attention from historians than those in the Atlantic Theater. The major, tide-turning naval battles between carrier fleets were fought in the Pacific while decisive, turning points in the Atlantic Theater were land battles, specifically at Stalingrad and El Alamein. Historian Evan Mawdsley contends that the war for the Atlantic was considerably more important for the Allies than the war in the Pacific. Accordingly, the relatively unsung contributions of carriers in the Atlantic, which made these victories possible, may warrant more appreciation.Mawdsley, pp. 475–476
Commanders, organizations, and strategies (1939 - 1945)
Unlike in the Pacific Theater, where naval commanders exerted the principal influence on operations, war in the Atlantic Theater was closely directed by the heads of government, namely Adolf Hitler, Winston Churchill, Joseph Stalin, and Franklin Roosevelt. The first three frequently involved themselves in operational details, while Roosevelt was more inclined to leave such details to his military commanders.