Given the disparity in strength between the German Navy (Kriegsmarine) and the Royal Navy, German strategy at sea during World War II was to avoid a traditional naval battle and attack Allied merchant shipping with surface raiders and submarines (U-boats). These attacks on maritime trade served multiple purposes. The threat alone forced Britain and France to put merchant ships into inefficient convoys, while the difficulties of spotting and tracking U-boats required the dispersal of large numbers of planes and escorts for trade defense. In addition, the cumulative total of cargo ship losses would reduce overall transport capacity and reduce the amount of cargo shipped overseas. The role of surface raiders in this campaign was to evade enemy patrols in European waters and then sink as many merchant ships as possible in a sudden descent on the Atlantic trade routes. A side benefit of these operations would be the disruption of the merchant ship convoy cycle, which had secondary and tertiary effects on Allied resource mobilization, war production, and troop deployments.
The main tools used by the Kriegsmarine in this campaign were the three Panzerschiffe (pocket, or small battleships) Lutzow, Admiral Graf Spee, Admiral Scheer, two heavy cruisers (Admiral Hipper and Prinz Eugen), two battle cruisers, (Scharnhorst and Gneisenau), and a fast battleship (Bismarck). All of these warships were relatively new, the oldest being Lutzow, and she was launched in 1931. They had good range, were faster than most Allied battleships, and were well-armed compared to most British and French anti-commerce raiding forces. The Germans also equipped armed merchant ship auxiliaries as raiders, which had the advantage of "camouflage" when sailing in far off waters such as the Indian Ocean and the Pacific.
Unfortunately for Germany, the surface raiders had little success early in the war. Lutzow made a long but unsuccessful cruise in October 1939, while Admiral Graf Spee was hunted down and forced to scuttle in the Rio de la Plata, Uruguay, two months later. The pair only sank eleven merchant ships between them. These poor results were caused in part by the restricted geography of the North Sea, with German Navy bases being concentrated in the southeastern corner. In the summer of 1940, however, the collapse of Norway, the Low Countries, and France dramatically improved Germany's strategic position. No longer could the Royal Navy easily "bottle up" Axis forces in restricted waters. To make matters worse for Britain, attacks from newly-established bases in France outflanked British defenses and stretched British patrol aircraft and escorts to the breaking point.
In response to this disaster, American policy began to shift away from neutrality. On 27 June 1940, President Franklin D. Roosevelt declared a national emergency and began American efforts to control shipping in the western hemisphere. In August, as part of informal staff talks between American and British officers, the U.S. sent military officers to observe Commonwealth operating procedures. As part of this process, and to familiarize the British with American-built seaplanes (London had ordered 200 such aircraft), U.S. Navy officers soon began flights in Coastal Command Catalina patrol aircraft. In addition, on 2 September, the United States government provided the Royal Navy with 50 over-age destroyers in return for leasing agreements on British bases in the Bahamas, Antigua, St. Lucia, Trinidad, Jamaica, and British Guiana. American forces began shifting into these bases over the next few months, strengthening the Atlantic Squadron's ability to patrol and watch over American waters.
In December 1940, German raiders Admiral Scheer and Admiral Hipper put to sea. These warships, together with the two battlecruisers that sortied during the first quarter of 1941, evaded British patrols and sank 47 Allied merchant ships. These actions disrupted British convoy defenses and severely dislocated the flow of shipping across the Atlantic. German U-boats took advantage of the confusion and sank another 138 merchant ships over the same four-month period.
In response to these raids, the U.S. Navy established the Support Force, Atlantic Fleet on 1 March 1941. Composed of destroyers, seaplane tenders, and patrol plane squadrons, it was intended to provide protection for convoys in the North Atlantic. On 26 April, American patrols were pushed southward in the Atlantic to 20 degrees below the equator. This extension by enabling American carrier task groups to patrol the South Atlantic, allowed the British to concentrate their forces in northern waters. On 18 May, patrol squadron VP-52 at Argentia, Newfoundland began patrol operations from seaplane tender USSAlbemarle (AV-5).
In an attempt to continue their successes from earlier in the year, the Kriegsmarine sent battleship Bismarck and heavy cruiser Prinz Eugen on a raid into the Atlantic on 20 May 1941. Spotted by observers in the Kattegat (near Sweden) who quickly alerted the British, Royal Navy patrols were increased. The two warships subsequently were sighted by cruisers Suffolk and Norfolk in the Denmark Strait. Through skillful seamanship, the cruisers managed to shadow the German raiders and send in repeated spotting reports, allowing the Royal Navy's Battle Cruiser Squadron to close on the area.
On the morning of 24 May, the German warships were engaged by battleship Prince of Wales and battlecruiser Hood. As the British squadron closed the range, Bismarck and Prinz Eugen concentrated their fire on Hood. After a German salvo straddled the battlecruiser at a range of about 18,000 yards, Hoodblew up in a huge explosion that erupted between her after funnel and the mainmast. Only three survivors from her company of 95 officers and 1,324 men were rescued. Outgunned and damaged by German shell hits that followed almost immediately, Prince of Wales broke off the action and retired under a smoke screen.
The German battleship, however, had not escaped unharmed. Two 14-inch shells from Prince of Wales had hit Bismarck, one of which caused a fuel leak and contaminated several oil bunkers with salt water. Unable to contemplate continuing her mission, Bismarck turned southeast and headed for Brest, in German-occupied France. Just after dusk, in order that the German cruiser might attack Allied shipping in the mid-Atlantic, Prinz Eugen broke away to the southwest and escaped. British naval forces continued to converge on the area and, just after midnight on 25 May, a strike by nine Swordfish aircraft launched from aircraft carrier Victorious managed to hit Bismarck with one torpedo. The damage proved minor, however, and the British prepared to launch another attack in the morning. Unfortunately, about an hour later both Suffolk and Norfolk lost contact with the German battleship, and she too slipped away in the darkness.
Many anxious hours passed for the British, particularly as they assumed wrongly that Bismarck was retiring to the northeast. All hopes for finding her again rested on the many warships closing the area or in the long-range patrols by Coastal Command aircraft squadrons flying out of Britain and Iceland. In addition, many American patrol aircraft, including patrol squadron VP-52 out of Argentia, flew long search patrols in the waters of the western Atlantic. All these air patrols were made more difficult and dangerous by high winds, rain squalls, and low cloud cover.
It was not until 1010 on 26 May that British luck changed. A British Catalina aircraft of No. 209 Squadron, piloted by US Navy observer Ensign Leonard B. Smith, USNR (US Naval Reserve), spotted Bismarck at a range of about eight miles. While Ensign Smith flew the aircraft and evaded accurate German antiaircraft fire, his British copilot radioed a report of the enemy warship's location
Although the German battleship had avoided many British patrols and was only 670 miles northwest of Brest, she was still far from the safety of German Air Force (Luftwaffe) air cover. Still, it would prove difficult for the Royal Navy to catch Bismarck, as the British Battle Squadron was too far north. Fortunately for the British, the aircraft carrier Ark Royal in Force H from Gibraltar found herself southeast of Bismarck's reported location and directly in the path to Brest. Upon acknowledging the contact report, cruiser Sheffield was detached from Force H and ordered to find and shadow the enemy. Later that day, naval observer Lieutenant James E. Johnson in a British Catalina from No. 240 Squadron, relieved Smith's plane and maintained contact with the German battleship until Sheffield took up a shadowing position.
Following an abortive air strike that afternoon in which fourteen Swordfish mistakenly attacked (but missed) Sheffield, a second strike of fifteen Swordfish took off from Ark Royal at 1910 that evening. Over the next hour or so, in conditions of low clouds, strong winds, and fading daylight, the aircraft released thirteen torpedoes in a series of attacks against the German battleship. While the poor weather made these attacks difficult, it also threw off the aim of the German antiaircraft gunners, and no planes were lost. Two torpedoes struck Bismarck, one with little effect, but the other wrecked her steering gear and jammed the rudder. This lucky blow sealed her fate. Slowed to a crawl by the damage, Bismarck could no longer escape her converging pursuers.
After midnight on the 27th, one Polish and four British destroyers closed the range and made multiple torpedo attacks on Bismarck. A few hours after dawn, the British heavy warships steamed into view, and battleships King George V and Rodney engaged Bismarck at a range of 16,000 yards. German gunnery was inaccurate, probably owing to crew exhaustion, and after an hour and a half Bismarck was reduced to a blazing shambles. Torpedoed twice more, and eventually scuttled by her surviving crew, the German battleship sank some 300 nautical miles west of Ushant, France. Only 110 of her crew of 2,222 survived the sinking.