Germany started World War II in a formidable position both on land and in the air, but its navy clearly suffered in comparison to the fleets of Britain and France. Indeed, the Allies' advantage on the high seas was greater than it had been during World War I. It became even more pronounced with America's entry into the conflict. But as the war continued, it became obvious that Germany's only chance of defeating the British lay in the Atlantic Ocean. This was due to Britain's dependence on the importation of vast quantities of food, raw materials, military supplies, and equipment. If the Germans could reduce that flow to a critical level, they might yet force the British to abandon hostilities. The key to such a possibility was the submarine (Unterseeboot in German - U-boot for short, and U-boat in English). If Germany could produce enough of these U-boats and sink enough Allied ships, they might get the job done. Conversely, the key to Britain's survival was the development of antidotes for the submarine menace. The ongoing struggle to achieve these opposing aims became known as the Battle of the Atlantic.
THE BALANCE OF POWER AT SEA
When the war began, the Germans possessed 57 submarines, only 22 of them suitable for operations in the Atlantic. The remainder were intended for duty in coastal waters or for training. Admiral Raeder, the commander in chief of the German navy, and Admiral Karl Donitz, commander of the submarine service, realized that such a meager force could not inflict serious damage. And since both the army and the Luftwaffe received production priority over the navy, a large U-boat force would not be available for at least two years. In addition, Raeder hoped to strengthen his surface fleet, which also diverted resources from U-boat construction.
Raeder, who had received the navy's top post five years before Hitler came to power, wanted a balanced fleet that would include a large submarine force as well as a formidable surface component with numerous battleships. There was one major flaw in his approach, however. Such a fleet would only begin to assume powerful dimensions in 1943 and would not reach completion until 1948. Much of the problem was due to Raeder's belief in Hitler's claim that there would be time for a major construction program before the outbreak of war. He also accepted the Fuhrer's assurances that Britain would remain neutral.
But since hostilities came in 1939, and because contrary to Hitler's soothing words, Britain was arrayed against Germany, the surface fleet was also at a hopeless disadvantage in relation to the Royal Navy. It included three "pocket battleships" - Deutschland, Admiral Scheer, and Admiral Graf Spee. These vessels were products of the limitation of German naval construction under the Treaty of Versailles to warships of 10,000 tons or less. The pocket battleships actually exceeded this restriction by 2,000 tons but were of light construction and possessed six 11-inch guns, which made them more powerful than much faster ships and faster than most vessels that were better armed. German naval leaders intended them as surface raiders that would prey on enemy merchant shipping. Other elements of the surface fleet included two battle cruisers of almost 32,000 tons - Scharnhorst and Gneisenau - as well as eight cruisers and 21 destroyers. Two 42,000-ton battleships of the latest design - Bismarck and Tirpitz - along with the heavy cruiser Prinz Eugen were under construction and would not be available until 1941.
By contrast, the Royal Navy had 15 capital ships and another five battleships under construction. The British also possessed 62 cruisers, seven aircraft carriers, 69 destroyers, and 75 submarines. With this discrepancy in their favor, the Allies instituted a blockade of Germany, but it initially proved less than successful because the Germans were able to obtain most of the raw materials they needed from the Soviet Union and Eastern Europe.
THE U-BOAT: KEY TO VICTORY?
Unlike Raeder, Donitz had assumed all along that Britain would fight Germany in the next war and recognized that the submarine was the only weapon that could be decisive against the British in the North Atlantic. He had served for two years on submarines during World War I. This experience prompted him to push hard during the interwar years for the formation of a large U-boat force. Donitz worked tirelessly to perfect submarine tactics that featured mass attacks on enemy convoys. Far more approachable than the austere Raeder, Donitz enjoyed extremely close relationships with his subordinates.
When the war began, Donitz did what he could with his limited forces to launch a submarine campaign against the Allies. Its first victim was the British passenger liner Athenia. Although the facts are still not completely clear, the commander of U-30 apparently mistook the vessel for an auxiliary cruiser and torpedoed it. Loss of life was relatively light: Of 1,417 aboard, 112 perished. British leaders denounced the Germans for committing a deliberate atrocity, but Hitler actually deplored the sinking of the Athenia, and he ordered his submarine commanders to refrain from any further attacks on passenger ships. The Fuhrer hoped to entice Britain and France to make peace once Germany had defeated Poland. This made him reluctant to precipitate any incidents that might provoke continued hostility on their part.
German U-boats scored a number of successes in the following months. The first of these came on September 17 with the sinking of the British aircraft carrier Courageous. The most spectacular occurred on the night of Friday, October 13, when U-47, commanded by Lieutenant Commander Gunther Prien, penetrated the Royal Navy's main base at Scapa Flow in the Orkney Islands north of Scotland. The submarine sank the battleship Royal Oak and escaped without a scratch. U-boats also took a heavy toll of British shipping, considering their small numbers. By March 1940, they had sunk 222 ships, a total of 886,000 tons. But the Germans paid a stiff price, losing 15 of their previous few U-boats.
Germany enjoyed the advantage of having broken the Royal Navy's cipher before the war. This gave the Germans valuable information on British naval dispositions. Although the Admiralty developed protection for its cipher by the fall of 1940, the Germans compensated for this by breaking the British and Allied merchant ship code. This provided their U-boats with detailed intelligence on merchant traffic and contributed to many sinkings until the summer of 1943.
COMBATING THE U-BOAT
The British resorted to the convoy system, which they had used to good advantage in World War I. This involved grouping large numbers of merchant ships and escorting them by warships, especially destroyers. But Churchill, as first lord of the admiralty and later as prime minister, was not convinced of the value of close escort of convoys. He preferred wide sweeps by naval ships to hunt down submarines. In line with his desires, warships split their duties between escorting convoys and running search-and-destroy missions. The results were disappointing. U-boat sinkings were few, while the skeleton escorts had difficulty fending off submarine attacks on convoys. Churchill proved hard to convince, however, and did not change his policy until 1942, when convoys received larger close escorts.
Escort vessels were fortunate to have the assistance of sonar (sound navigation and ranging), a high-frequency device that could detect submerged U-boats. The British called this system asdic (anti-submarine devices investigation committee). But asdic was not a miracle weapon. It could not detect submarines on the surface, and U-boats usually attacked at night while surfaced. It could detect the range and bearing of submerged submarines, but it could not determine their depth. U-boats were often able to escape destruction by diving to 400 feet, thus avoiding depth-change patterns.
An additional 900,000 tons of Allied shipping fell victim to mines and surface raiders from the outbreak of the war to the end of February 1940. Indeed, for a time a new weapon, the magnetic mine, loomed as the greatest menace of all to the British. At first, it proved impervious to mine sweeping because, unlike conventional mines, which were extended from anchors by cables, the magnetic mines came to rest on the bottom in shallow water. When a ship's steel hull passed over such a device, it interfered with the earth's magnetic field and triggered the mine. Unfortunately for the Germans, the British soon discovered a remedy by attaching cables to their ships that set off electrical charges and desensitized the hulls of the vessels.
The most dramatic episode in the early days of the war at sea came in connection with attacks by surface raiders. Two of the pocket battleships, Deutschland and Admiral Graf Spee, had penetrated into the Atlantic shortly before the war. They received service from tanker supply ships that waited for them at prearranged locations in waters off the usual shipping routes. Deutschland sank only two vessels before returning to Germany. Hitler had worried about the propaganda effect of losing a ship named Deutschland, so after its return, he promptly renamed it Lutzow, after the flagship of the German battle cruiser squadron in the Battle of Jutland.
Graf Spee was more fortunate, at first. Operating in the South Atlantic and the Indian Ocean, where there were fewer Allied warships, it found easy prey, sinking nine merchant ships. But on December 13, Graf Spee encountered a small Allied squadron consisting of the heavy cruiser Exeter and two light cruisers, Ajax and Achilles, off the coast of South America. Although the pocket battleship outgunned all three enemy vessels and thus could shell them safely from long range, its commander, Captain Hans Langsdorff, made the mistake of closing on his adversaries. In the ensuing battle, Graf Spee disabled Exeter, which had to break off the action, but Langsdorff's ship also sustained some damage. He decided to put in for repairs and refueling at Montevideo, the capital of Uruguay and a major port on the estuary of the Plate River. This proved to be his second mistake. The Uruguayan government responded to British diplomatic pressure by terminating the vessel's stay before the repairs had been completed.
In the meantime, the heavy cruiser Cumberland joined Ajax and Achilles, which were waiting offshore. Langsdorff now faced three options: internment for the duration of the war, another battle with the British cruisers, or scuttling his ship. He chose the third. On December 17, Graf Spee steamed out into the Plate estuary where scuttling charges tore the ship apart. Langsdorff and his crew took refuge across the river in Buenos Aires, Argentina. The captain wrapped himself in an imperial German flag to show his contempt for Hitler and shot himself in his room the next night.
Despite the losses that the Germans had inflicted on Allied shipping during the first six months of the war, U-boat attacks were not yet more than a highly annoying nuisance. Nevertheless, Britain's prospects in the war at sea received two serious blows during the summer of 1940: the fall of France and the entry of Italy into the conflict. Not only would the British lose the support of France's sizable navy, but Churchill feared that it would fall under Germany's control, greatly altering the balance of power on the high seas. It was this grim prospect that prompted Churchill to order the attack on French naval vessels at Mers-el-Kebir and Oran in July. Ironically, the operation, which naturally worsened relations between Britain and a recent ally, was quite unnecessary. Vichy leaders were determined to keep their fleet in French hands.
THE STRUGGLE FOR THE MEDITERRANEAN
The Italian navy was another matter. A formidable presence in the Mediterranean, it included two modern 35,000-ton battleships, four old but modernized 23,000-ton battleships, 18 cruisers, more than 60 destroyers, a similar number of torpedo boats, and 100 submarines. This submarine force was the largest of any of the belligerents'. Italian surface ships generally were faster and possessed longer-range guns than their British counterparts. Their chief weakness was their relatively thin armor, which made them vulnerable to direct hits. Italy's numerical superiority was a source of deep concern to Admiral Sir Andrew Cunningham, the commander of Britain's Mediterranean Fleet based at Alexandria in Egypt, and Admiral Sir James Somerville, who commanded Force H based at Gibraltar.
Cunningham had gained a reputation as an aggressive destroyer commander during World War I but by 1937 appeared headed for retirement. The worsening international situation spared him this fate and led to his appointment to the crucial Mediterranean post before the outbreak of war. Somerville actually had retired in 1938 after a short illness but returned to service in 1939. He helped organize the Dunkirk evacuation and took over Force H after the fall of France.
On the night of November 11, 1940, the British carrier Illustrious launched an attack by 21 Swordfish bombers against the Italian naval base at Taranto. The Swordfish were antiquated fabric-covered, open-cockpit biplanes, and their lack of speed made them highly vulnerable to antiaircraft fire. They could deliver their strike only at night. Ten of the Swordfish dropped flares to illuminate the harbor and bombed shore installations. The remaining 11 launched torpedoes against the ships lying at anchor. They knocked one modernized old battleship out of action permanently and crippled two other battleships, including the new 35,000-ton Littorio, as well as two cruisers. The disaster forced Italian naval leaders to shift all remaining major ships to Naples and other, more remote ports on Italy's western coast, where they would be safe from British attack. In January 1941, German dive bombers, in their first action in the Mediterranean, gained a considerable measure of revenge for their ally's defeat at Taranto when they disabled Illustrious.
Cunningham's fleet scored another triumph in March 1941, shortly before the German invasion of Greece and Yugoslavia. An Italian squadron, led by the new battleship Vittorio Veneto and comprising 8 cruisers and 13 destroyers, attempted to intercept a British convoy transporting ground forces to Greece. But British cryptanalysts had broken the Italian naval cipher and provided Cunningham with vital information on the enemy's intentions. In an engagement fought off Cape Matapan, the southernmost tip of the Greek mainland on the 28th, British torpedo bombers from the aircraft carrier Formidable and twin-engined Blenheim bombers from Crete damaged Vittorio Veneto and crippled the heavy cruiser Pola. Admiral Angelo Iachino returned to Taranto with his battleships, but that night Cunningham's battleships finished off Pola as well as two other heavy cruisers and two destroyers.
Despite the disasters of Taranto and Cape Matapan, the Italian navy had far greater success escorting Axis troop and supply convoys to North Africa. Italian submarines and light surface units, working in cooperation with German and Italian aircraft, also made it exceedingly difficult for British convoys to reach the island base of Malta. Lying only 70 miles south of Sicily, Malta posed a problem for Axis convoys because it lay astride their route to Libya. The British maintained a small number of cruisers and destroyers there as well as an air contingent. These forces attacked Axis convoys during the summer of 1941 and resulted in Raeder's decision to shift six U-boats to the Mediterranean. The submarines proved effective, sinking the carrier Ark Royal and the battleship Barham. But the Italians carried out the most spectacular operation of that year when a submarine launched three slow-moving, electrically operated torpedoes near Alexandria in December. Two frogmen guided each torpedo through the harbor's defenses and deposited them under the battleships Queen Elizabeth and Valiant and a tanker. Explosions destroyed the tanker and seriously damaged both battleships.
German planes also began to attack Malta in January 1942, and the British reinforced the island's meager air strength in June. Many have hailed Malta as a critical factor in Britain's eventual victory in North Africa, but they may have exaggerated its importance. Approximately 86 percent of all materiel shipped to Axis forces arrived safely in Libya between 1940 and November 1942, and the British suffered heavily in their efforts to keep the island supplied. They paid their highest price in ships and lives in August 1942, when a large naval force escorted a convoy of 14 merchantmen from Britain to Malta by way of the Strait of Gibraltar. Axis submarines and air attacks sank all but five of the supply ships as well as the aircraft carrier Eagle, two cruisers, and a destroyer and severely damaged another carrier and two more cruisers. Malta may have been more of a liability than an asset.
THE BATTLE OF THE ATLANTIC CONTINUES
Meanwhile, Germany's victories in Norway and France in the spring of 1940 had provided bases on the Atlantic for submarine and surface raiders as well as aircraft. French bases proved superior to those in Norway because of the greater size of the harbors and their proximity to British shipping lanes. The Germans built concrete submarine pens up to 30 feet thick that were impervious to air attack in French ports. Air bases in France and Norway also provided Germany with its only opportunity to experiment with a long-range bomber, the Focke-Wulf 200 Kondor, which was actually a converted airliner and transport plane. Although the Kondor was slow and vulnerable to fighter planes, during 1940 and much of 1941 British convoys lacked such fighter support. This enabled Kondors along with medium bombers to destroy 580,000 tons of shipping in 1940 and over a million tons in 1941. With the advent of British escort aircraft carriers in September 1941, this threat quickly diminished.
Although U-boats were still not numerous enough to constitute a war-winning force, they sank over 1.6 million tons of shipping from June to November 1940, a period that U-boat crews referred to as the "happy time." These losses worried the British, whose naval resources were stretched dangerously thin. Escort vessels were at a premium, but the development of the corvette, a small vessel of only 925 tons, helped ease the problem. Britain produced large numbers of them in relatively short order. Though lacking the speed and punch of destroyers, corvettes greatly strengthened convoy escorts.
Sinkings tapered off during the winter of 1940-41 because of the difficulty that submarines encountered in bad weather but mounted again in the spring and summer. Donitz made increasing use of "wolf pack" tactics, which employed a number of U-boats working together. Usually, one submarine would locate a convoy and alert other U-boats in the area by wireless. They would then attack the convoy at night while operating on the surface, where they had an advantage in speed over most escort vessels.
Despite the persistent submarine and bomber menace, aid from North America helped brighten Britain's outlook. The Royal Canadian Navy created an escort force in June 1941 that provided protection for convoys between Newfoundland and Iceland. In April, the United States established air bases in Greenland, and in July, U.S. forces relieved British troops in Iceland. During July, Roosevelt ordered American air and naval forces to patrol the western Atlantic and warn British convoys of the presence of German submarines. The United States's lend-lease program also included constructing both naval ships merchantmen for Britain as well as providing refitting facilities for British ships in American ports. In September, America undertook the responsibility of escorting convoys to a midocean meeting point where British escorts took over, and in November, Congress authorized the arming of U.S. merchant ships and allowed them to carry cargoes to belligerent ports.
Britain also benefitted from Ultra. The German naval cipher had proved especially difficult to break, but in May 1941, a British destroyer crew captured submarine U-110's cipher machine and code books. The destroyer had severely damaged U-110 and its commander had ordered his men to abandon ship after setting demolition charges. But these had failed to detonate. This stroke of fortune enabled the Royal Navy to amass a vast glut of information on U-boat strength and positions as well as plans for attacking convoys. Although this intelligence certainly did not end the submarine menace, it helped prevent the Germans from achieving greater success.
During the period from April to December 1941, Axis submarines sank over 1.5 million tons of shipping, but only one-third of the victims were members of convoys. A definite decline in sinkings occurred between October and December, and it appeared that the British might be getting the better of the Battle of the Atlantic. But this improvement was short-lived.
It was also during the period 1940-41 that German surface raiding reached tis peak. Disguised merchant ships led the way, starting in April 1940. These were equipped with 5.9-inch guns that gave them the firepower of most light cruisers. They also carried torpedoes and received supplies from ships that waited for them in quiet waters. Seven of these raiders sailed at various times between March 1940 and November 1941. They accounted for 65 merchantmen with a total tonnage of 435,000. But with the aid of detailed Ultra intelligence, British warships sank three of them and, starting in the summer of 1941, hunted down and destroyed most of their supply ships.
Ironically, German surface warships were less productive, due largely to their shorter range and Hitler's reluctance to allow them to take risks. The pocket battleship Sheer enjoyed the most success. It sank 16 merchant ships totaling 99,000 tons as well as an armed British merchant cruiser between October 1940 and April 1941. The cruiser Hipper carried out two raids in late 1940 and early 1941, sinking nine vessels of over 40,000 tons. And during the first three months of 1941, the formidable battle cruisers Scharnhorst and Gneisenau destroyed 22 ships with a total tonnage of 116,000 before taking refuge in the French port of Brest.
BISMARCK'S FIRST AND LAST VOYAGE
By far the most famous of these sorties, though certainly not the most successful, was that of the newly commissioned battleship Bismarck and the heavy cruiser Prinz Eugen in May 1941. Under the command of Admiral Gunther Lutjens, these powerful ships left Bergen, Norway, on May 21 and ventured into the Atlantic. RAF reconnaissance planes discovered them the same day and alerted the British main fleet. The cruisers Norfolk and Suffolk sighted the German ships in the Denmark Strait between Iceland and Greenland on May 23, while the battle cruiser Hood and the new battleship Prince of Wales closed in for a showdown. Prince of Wales was still undergoing tests on her armament and, in fact, sailed with construction workers on board. Hood was Britain's largest ship but dated from 1920 and had poor armored protection. In the predawn twilight of May 24, the opposing ships opened fire at a range of 14 miles. A shell from Bismarck plunged through Hood's weak deck armor and into a magazine. The ship immediately blew up, killing all but three of the crew of 1,400. Both Bismarck and Prinz Eugen also hit Prince of Wales with several shells, forcing it to break off action.
The two German ships continued on their way, with Norfolk and Suffolk shadowing them at a safe distance until the main British fleet, some 300 miles away, could arrive. But Bismarck had suffered damage from Prince of Wales' shells, most notably an oil leak that forced Admiral Lutjens to abandon his raid into the Atlantic and head for the French port of St. Nazaire at reduced speed instead. Lutjens sent Prinz Eugen ahead, and that ship reached Brest on June 1.
Although Bismarck's pursuers lost contact on May 25, a Catalina flying boat discovered the ship the following day. Soon afterward, Swordfish torpedo planes from the carrier Ark Royal attacked Bismarck, and one of the torpedoes jammed the ship's rudder, leaving the vessel helpless. When the British battleships King George V and Rodney finally caught up with the stricken vessel, they pounded it with armor-piercing shells and left it a flaming hulk. The cruisers Norfolk and Dorsetshire attempted to finish the job with torpedoes, but they proved ineffective against Bismarck's strong armor. The ship did not finally succumb until the crew scuttled it to prevent the pride of the German navy from being captured by the British.
Dorsetshire and a destroyer lingered to pick up survivors. They had rescued 110 of Bismarck's 2,300-man crew when Dorsetshire sighted a German submarine. The two ships looked to their own safety and steamed away at a high speed. The U-boat's untimely appearance ironically condemned many German sailors who were still in the water to death. The submarine could save only three. The loss of Bismarck for all practical purposes ended the efforts of German surface craft to play a major role in the Battle of the Atlantic.
But Scharnhorst, Gneisenau, and Prinz Eugen all remained at Brest. Although well situated for additional sorties into the Atlantic, they were also vulnerable to Allied air and naval attack and remained immobilized until February 1942. By that time, Hitler had become convinced that the Allies planned to invade Norway and insisted that the three cruisers leave Brest and take up positions in northern waters. The only way in which they could possibly accomplish this was by a dangerous dash through the English Channel, where the British would almost certainly attack them. The Germans, accordingly, carried out mine-sweeping and radar-jamming operations in advance, and the cruisers left Brest with a destroyer escort on the night of February 11. When daylight came, they were only halfway through the channel. Despite Ultra warnings that the Germans were planning a channel dash, the British did not detect the ships until late in the morning. German fighters fought off RAF attacks, and the squadron continued its escape. Although both Scharnhorst and Gneisenau struck mines and suffered minor damage, all three ships found refuge in German ports.
Russia's entry into the conflict in June 1941, while clearly a major turning point in the war, added to the drain on British naval resources. Churchill shifted a large number of ships to transport war materiel to the Soviets. The transformation of the United States into a full-fledged belligerent in December 1941 also greatly enhanced Britain's prospects. But Japanese attacks on British possessions in East Asia compounded Britain's already heavy naval commitments and led to the loss of two more capital ships - Prince of Wales and Repulse in December 1941. Moreover, many American vessels, which had been cooperating with the British in the North Atlantic, now served their own country. And ships under construction in the United States that might otherwise have gone into the British navy or merchant marine joined the U.S. Pacific Fleet.
CRISIS AND RESOLUTION IN THE NORTH ATLANTIC
The Battle of the Atlantic reached its most critical stage during 1942. Admiral Donitz estimated that sinkings of Allied shipping must average 700,000 tons per month if the Germans were to win the struggle. They had averaged only 180,000 tons during 1941. In an effort to reach this goal, Donitz sent as many U-boats as he could spare to American waters. Although the number actually operating there never exceeded a dozen, they accounted for almost half of the tonnage that submarines sank between January and April and took an especially heavy toll of tankers. One of the chief reasons for this remarkable success was the U.S. navy's reluctance to group merchant ships in convoys unless they were protected by strong escorts of warships. Since the latter were in short supply, they refused to organize convoys at all, making merchant vessels easy prey for U-boats. A lack of trained crews and officers added to the problems. To make matters worse, for some time the United States did not impose a blackout on eastern seaboard cities. Merchant ships and tankers, silhouetted against this brightly illuminated background, provided perfect targets for U-boats operating at night. Submarine commanders later looked back on this period as the "second happy time" and the "American shooting season."
Allied losses during February, March and April hovered near the 500,000-ton mark. In May, they rose to 600,000 and in June exceeded Donitz's magic number of 700,000. The Germans also contributed to this success by changing the cipher used by their submarines in February. British cryptanalysts were not able to penetrate the new cipher until December, although they continued to detect other enemy naval messages. Belated American adoption of the convoy system and improved antisubmarine methods cut July sinkings to under 500,000 tons. The new techniques included a refined airborne radar that made it possible for aircraft to locate U-boats on the surface at night and attack them with the aid of searchlights. But the Germans adjusted to this by installing receivers in their submarines that could detect the impulses emitted by the radar of approaching enemy planes. This enabled the U-boats to dive before such aircraft arrived. In the summer of 1942 the Allies also began to place high frequency radio detectors (HF/DF or "Huff-Duff") on their escort ships. These devices enabled them to locate U-boats through their radio transmissions.
The Germans increased their submarine strength to over 300 in August, about half of which were operational. These included larger vessels that had a range of 30,000 miles and could dive much deeper than earlier models. Sinkings once again climbed over 500,000 tons in August and continued to increase during the following months, reaching a high of over 700,000 in November. During all of 1942, the Allies lost 1,664 ships with a tonnage of almost 7.8 million to all causes, over 80 percent to submarines. These losses ran almost a million tons ahead of new Allied shipping that came into service during 1942.
Early in 1943, Hitler angrily threatened to scrap all German surface ships after the failure of an attack by a force of cruisers and destroyers on a Russia-bound convoy in the Barents Sea. Admiral Raeder responded by resigning as commander in chief of the navy, and Donitz succeeded him. The new commander vowed to step up the U-boat campaign and managed to persuade Hitler not to eliminate the surface fleet. After a lull during December 1942 and January 1943, due largely to bad weather, submarine attacks increased in February and reached alarming proportions during the first three weeks of March, when wolf packs accounted for over 600,000 tons.
But sinkings declined precipitously, starting in the last week of March and continuing into April and May. The key to this abrupt change was a new coordinated antisubmarine offensive instituted by British Admiral Sir Max Horton, who became commander in chief of Allied naval forces in the western approaches to the British Isles in November 1942. A submarine commander during World War I, Horton had been in charge of British home-based submarines since 1940. His knowledge of underwater craft as well as his great drive and willingness to experiment served him well in his new position. He devised methods that brought much greater pressure to bear on U-boats, and he proved more than a match for Donitz. The restored ability of Ultra to decipher German messages flowing between U-boat captains and Submarine Command proved of crucial importance. Without it, Horton would not have been able to direct his offensive with such pinpoint accuracy. Ultra information also convinced the Admiralty that the enemy had penetrated its convoy code and led to the adoption of a replacement, which proved secure.
Horton developed large support groups of destroyers and frigates, small warships that were faster than corvettes. These support groups aided convoy escorts by hunting down and destroying submarines operating in nearby waters. Horton also provided increased air support from both escort carriers and shore-based aircraft. These planes had the advantage of a new and revolutionary short-wavelength radar that German U-boats could not detect. Finally, improved depth charges and new rocket weapons also contributed to the remarkable reversal of fortunes. Not only did it become more difficult for U-boats to sink ships, but they found themselves hounded as never before. The climax came in May, when the Germans lost 41 submariners. The toll was so prohibitive that on May 23, Donitz withdrew his forces from the North Atlantic. During the summer of 1943, the Allies built more ships than they lost. They had won the battle of the Atlantic.
But the struggle was not yet over. Donitz devoted himself to enlarging and improving the quality of his submarine force. He and his colleagues introduced the snorkel, a collapsible air intake and exhaust release mast that barely protruded above the surface and enabled submarines to remain continuously submerged. The homing torpedo, which was acoustically attracted by an enemy ship's propellers, also came into operation. But the Allies foiled this formidable weapon by developing the foxer, a device that a ship towed at a safe distance behind it. The foxer made more noise than the vessel's propellers and thus diverted bombing torpedoes from their real targets.
The Germans also developed a formidable new submarine, the Walter type. This was a large U-boat that could remain underwater indefinitely. Thanks to a special perhydrol fuel, it was capable of such high speeds when submerged that it could outdistance most escort vessels. But it encountered a multitude of "teething" problems that proved so difficult to overcome that none of this type of submarine ever saw action. Two other smaller models, both equipped with snorkels, did go into mass production during the winter of 1944-45. But by that time it was much too late.
Donitz resumed the submarine offensive in September 1943, but it accomplished little, while the Allies destroyed 25 U-boats during the first two months. In early 1944, the Germans sank only three ships but lost 37 of their own craft. Donitz found these results so discouraging that in March he halted operations against convoys until the new submarines would be able to go to sea in strength - a day that never came.
SUPPLY ROUTES TO RUSSIA
Allied aid also continued to flow to Russia, utilizing three routes. The first was via the Arctic Ocean to the north of Norway and the USSR, bound for the ports of Murmansk and Archangel. The second extended through the Indian Ocean and Persian Gulf to Iran and then across the Caspian Sea. British and Soviet troops had occupied Iran in August 1941. The third, and least known, stretched across the North Pacific to the Soviet port of Vladivostok. In this case, the U.S. had taken advantage of Russian neutrality in the war against Japan by transferring some of its merchant ships to the Soviet flag, thus enabling their safe passage across the Pacific.
The Arctic route was by far the most dangerous. Here, too, both German U-boats and surface ships attempted to intercept convoys bound for Murmansk and Archangel. The Germans also had air and naval bases in Norway. In addition to submarines, by 1942 Germany had gathered most of its surface craft in Norwegian waters, including the battleship Tirpitz, the pocket battleships Scheer and Lutzow, and the heavy cruiser Hipper.
Allied convoys had to make much of the voyage to the Russian ports without benefit of air cover. The most severe German attacks came between March and July 1942, culminating in the tragic destruction of convoy PQ 17, which left Britain in late June. Admiral Sir Dudley Pound, the commander of the Royal Navy, received information that Tirpitz had put to sea with the apparent intention of attacking the convoy. Pound ordered the escorting cruisers to withdraw from the convoy, fearing that they would fall victim to the German battleship. He also ordered the merchant ships to scatter. But Hitler, fearing the loss of Tirpitz, insisted that it return to base. German submarines and aircraft carried out the mission instead and did so with deadly efficiency, sinking 23 of the 36 merchantmen.
Sobered by this disaster, the Allies did not dispatch another convoy until September, despite Stalin's bitter protests. The next convoy, PQ 18, received a much stronger escort, and although German U-boats and aircraft sank 13 ships, they suffered heavy losses themselves. A few convoys also made the Arctic run during the winter of 1942-43. But in March, the British halted this traffic for several months due largely to the critical situation in the Atlantic. When convoys resumed in November, they received more powerful escorts than ever before, including carriers.
In late December, Scharnhorst and its supporting destroyers attempted to intercept convoy JW55B. But the British battleship Duke of York and three cruisers received detailed Ultra reports of the German movements and laid a trap. They pummeled Scharnhorst with fire from their big guns. The battle cruiser proved extremely difficult to sink, however. It took direct hits from an estimated 25 shells and 11 torpedoes to send the vessel to the depths of the frigid Arctic. Only 36 of its crew of nearly 2,000 survived.
The last blow to German surface power came with the crippling and later sinking of Tirpitz. In September 1943, British midget submarines X-6 and X-7 damaged the huge battleship, which lay at anchor in northernmost Norway, putting it out of action for six months. Carrier-based planes attacked the vessel again in April 1944 and inflicted minor damage. RAF heavy bombers crippled it in September, and a second attack in November finally settled the issue. Six-ton bombs ripped into Tirpitz's hull and set off a magazine. Soon afterward, the ship capsized, carrying almost 1,000 men to the bottom.
NO GUARANTEED VICTORY
Of the 1,170 submarines that Germany possessed during the whole of World War II, the Allies destroyed 784. In all, U-boats sank 2,828 Allied merchant ships, comprising a tonnage of over 14 million. Allied shipping losses in the Atlantic and European theater of operations from all causes totaled 21.6 million tons. Had the Germans been able to develop their new submarines earlier and bring them into action in large numbers, the outcome of the Battle of the Atlantic might have been different. If the Allies had been able to speed up their timetable and employ some of their ultimately decisive methods at an earlier date, their victory might have come sooner. Since neither development came to pass, it was, as the Duke of Wellington said of his victory over Napoleon at Waterloo, "a damned close-run thing."