The swift collapse of France had caught Hitler and his military advisers by surprise. Contrary to the general belief, they had no master plan and had made no provisions for an invasion of the British Isles. Still believing that Great Britain could be pressured into an accommodation, Hitler, in fact, was looking the other way—east, toward the Soviet Union. In Hitler’s view, Stalin had exceeded the spirit of the Russo-German pact by a military occupation of the Baltic states of Lithuania, Latvia, and Estonia, and the Balkan provinces of Bessarabia and North Bukovina, which greatly strengthened Stalin’s hold on the east Baltic and placed Soviet forces perilously close to the rich Rumanian oil fields, Germany’s chief energy source.
In his meetings with Hitler, Admiral Raeder sought to deflect the Führer’s growing concern over Soviet moves and to stress the perils posed by the Royal Navy. It would be a grave mistake, Raeder insisted, to turn about and attack the Soviet Union before Great Britain had been neutralized by treaty or thoroughly defeated. That would replicate the Kaiser’s great mistake of 1914 and create the worst of all possible situations: a two-front war. Rather than go east, Raeder suggested, Germany should go south to the Mediterranean and with Spain’s connivance, capture the British naval base at Gibraltar. That would effectively put an end to British naval dominance in the Mediterranean and decisively assist Mussolini’s forces, which were attacking out of Libya toward Egypt to seize Cairo, the Suez Canal, and the other big British naval base at Alexandria. Absolute Axis control of the Mediterranean Basin would place Germany in a favorable position to exploit the oil reserves of the Middle East as well as the limitless raw materials of Africa.
As Hitler viewed it, the situation was not analogous to 1914. The main continental enemy, France, was already beaten and occupied. Norway was occupied as well. Great Britain was flanked on the east and south—isolated and just barely hanging on. She had no foothold on the continent nor any hope of obtaining one. The British naval blockade of Germany was no longer a factor: Germany controlled Norway and the entire French Atlantic coast from the channel to Bordeaux. This time Italy and Japan were allies, not enemies.* Japan posed a threat to the Soviet Union in the Far East, which would freeze significant Soviet forces in that sphere. The Soviet Army and Air Force were nothing—a collection of ill-equipped rabble. The Wehrmacht and Luftwaffe could utterly crush the Soviet Union in a matter of six to eight weeks.
No master plan emerged from these discussions. After the fall of France, Hitler more or less improvised German operations week to week. The Luftwaffe and all available forces of the Kriegsmarine were to mount maximum pressure against British air and maritime assets, with the aim of forcing Great Britain to the negotiating table. If psychological pressure failed to get the job done, as a last resort the Wehrmacht might consider an invasion of the British Isles. Meanwhile, Hitler secretly drew plans for the conquest of the Soviet Union to take place in the spring of 1941.
Raeder and the OKM adamantly opposed a Wehrmacht invasion of the British Isles. The Kriegsmarine was in no position to mount a major amphibious assault. Most of its big surface forces had been sunk, damaged, or worn out in the Norway operation. Only one heavy cruiser, Hipper, was combat-ready. Besides that, the Navy had no landing craft, no means of transporting troops, tanks, artillery, trucks, ammo, and other impedimenta across the channel. Nonetheless, the OKM drew up a contingency plan (Operation Sea Lion), which envisioned the use of hundreds of European river barges for landing craft.
There was one—and only one—possible way to assure a successful invasion of England. That was to first commit the Luftwaffe to the destruction of the RAF and the Royal Navy. When the Luftwaffe achieved absolute mastery of the air and seas, the barges—and even big passenger ships such as Bremen—could cross the North Sea and English Channel with confidence. The channel could be sealed at both ends by minefields and cordons of U-boats to block Allied submarine attacks—or surface ship attacks at night by remnants of the Royal Navy. But an invasion, Raeder continued to insist, should only be attempted “as a last resort.”
The Luftwaffe chief, Hermann Göring, was not keen on an invasion either. But he welcomed the opportunity to mount a full-scale air war against the RAF and Great Britain. He believed the Luftwaffe could wipe out the RAF in about three weeks and that denied this last line of defense, Britain would capitulate and sue for peace. He accordingly mobilized virtually the entire resources of the Luftwaffe for the task. Air Fleet 2 occupied bases in the Low Countries; Air Fleet 3 occupied bases in northern France; and Air Fleet 5 occupied bases in Norway and Denmark. Total resources: about 2,800 aircraft, of which about 1,600 were bombers or dive bombers and about 1,200 were fighters and reconnaissance planes.
Hitler made a final attempt to persuade the British people to lay down their arms in a speech to the Reichstag on July 19. Ridiculing Churchill’s defiant oratory, he said: “I feel it to be my duty before my own conscience to appeal once more to reason and common sense in Great Britain as much as elsewhere. I consider myself in a position to make this appeal since I am not the vanquished begging favor, but the victor speaking in the name of reason. I can see no reason why this war must go on.” Within one hour the answer was transmitted by BBC in London: Great Britain would not negotiate and it would never surrender.
The Luftwaffe air assault against the British Isles—the “Battle of Britain”—began on July 10. That day the RAF had about 2,000 aircraft in its inventory, of which about 1,200 were assigned to Bomber Command and Coastal Command and about 800 to Fighter Command. Since the Luftwaffe bombers and dive bombers were vulnerable and required escorting fighters, what counted most were the 700-odd Spitfires and Hurricanes of Fighter Command. The future of Britain depended upon the ability of these planes and pilots to knock out the 1,100-odd Luftwaffe fighters and get at the bombers.
Although Fighter Command had fewer fighters, it had the advantage of the Chain Home radar network and a highly efficient command-and-control organization. Thus the Hurricanes and Spitfires could be husbanded and shifted about to meet the greatest threat of the moment. Göring was aware of the British radar network, but having overwhelmed a similar French radar network with ease, he did not regard the British network as a serious threat nor did he even inform his pilots of its existence. Göring’s failure to knock out the British radar net—and the RAF command-and-control stations—was to be a fatal error.
The British had another intelligence advantage: Enigma codebreaking. Due to a procedural change on May 10 when Germany invaded France, the codebreakers lost Luftwaffe Red. However, in an amazing intelligence feat, within twelve days—by May 22—Bletchley Park had recovered Red and could read it consistently and currently. Luftwaffe Red yielded substantial—and valuable—strategic intelligence, such as the organization and administration of the Luftwaffe. It did not, however, provide what was needed most: tactical intelligence, such as how many German aircraft were to strike where and when.
The chief tactical items obtained from Red Enigma were to be occasional references to “Knickebein” (“Dog leg” or “Crooked leg”) and “X-Great” (“X-Apparatus”). The brilliant young civilian chief of RAF scientific intelligence, R. V. Jones, correctly guessed these were radio-beam navigational systems for night or foul-weather bombing. Put on the scent by Red Enigma and helped by POW interrogations and the recovery of hardware from a downed German plane, Jones confirmed this deduction. In due course he and RAF electronic technicians were able to predict probable targets from the beam settings recovered from Enigma and to devise clever methods of “jamming” (or “bending”) these beams, leading some German bombers to wrong and harmless targets. But that came later.
The Luftwaffe commenced the Battle of Britain with intense bombing attacks on British merchant-ship convoys in the Western Approaches and the English Channel. The main purpose of these attacks was to draw Fighter Command aircraft into combat and whittle them down in circumstances which favored the Germans. In the process, during July the German pilots sank thirty-three ships for about 70,000 tons. These losses and the threat of even greater shipping losses to German air attack led the Admiralty to divert convoys to more northerly routes into the British Isles, in effect closing down the Western and Southwestern approaches and complicating the task of the U-boats.
The new U-boat base at Lorient was ideally situated for attacks on British shipping, but Dönitz was unable to contribute significantly to the pressures on Great Britain in the month of July. Most of the oceangoing boats had returned to Germany for refits; only four oceangoing boats could sail from Lorient in July.
About the time the first of these, U-30, arrived at Lorient, B-dienst provided Dönitz with information about the attack by the Royal Navy on the French Navy at Oran and Dakar. Believing that further specific information from B-dienst might enable U-boats to intercept some of the British capital ships, Dönitz ordered Lemp to sail U-30 south to the vicinity of the Strait of Gibraltar, and the U-cruiser U-A, which was patrolling off the African coast, to close on Dakar.
Although U-30 and U-A had reported engine malfunctions, both attempted to carry out the missions. Lemp sailed from Lorient on July 13—the first U-boat into Lorient and the first to leave from there on patrol—but he was dogged by further engine trouble. After sinking a small ship—his seventh credited sinking since leaving Germany—Lemp was forced by engine malfunction to abort and return to Lorient. Northbound to Dakar from Freetown, Sierra Leone, Hans Cohausz in U-A sank his third ship, a 5,800-ton Norwegian freighter, but he, too, reported an engine breakdown and requested permission to abort and come home. Dönitz refused Cohausz permission, directing him to rendezvous with the German merchant raider Pinguin for repairs, refueling, and joint operations.
Meanwhile, B-dienst had provided Dönitz new information on North Atlantic convoys. Two significant changes in procedure had occurred: the shift to the northerly routes in reaction to the Luftwaffe attacks and creation of U-boat bases in France, and an extension of surface and air escort to 17 degrees west longitude, a line nearly 360 miles west of the British Isles. This put the likely rendezvous area northwest or west of Rockall Bank, which, with safe Atlantic routing, was about equidistant (about 1,000 miles) from Wilhelmshaven or Lorient. Hence, the advantages of mounting patrols against North Atlantic convoys from Lorient had been substantially reduced. The chief remaining advantage of Lorient over Wilhelmshaven in the war against North Atlantic convoys was the elimination of the slow, tedious voyage in and out of the confined, mined waters of the North Sea, which required running submerged in daytime to avoid enemy air and submarine patrols.
The extension of convoy escort to 17 degrees west longitude presented Dönitz with two major problems. First, in order to repeatedly attack an inbound convoy before it picked up its escort or an outbound convoy after it left its escort, U-boats had to operate well west of 17 degrees west longitude. Since this was beyond “British waters” where the unrestricted U-boat rules applied, Dönitz had to petition Hitler through Raeder and the OKM for a further relaxation of the rules. Second, operations so far to the west imposed restrictions on the use of Type VII boats, which had only half the fuel capacity of the VIIBs. In a prolonged convoy battle requiring high-speed running, even the VIIBs would be stretched. Hence fuel availability was to become a critical factor in most convoy battles.
With this new information in hand, Dönitz flew to Lorient on July 22 to confer with the skippers of the four oceangoing boats: Lemp (U-30), Rollmann (U-34), Salmann (U-52), and Kretschmer (U-99). After inspections and conferences, it was clear that U-30, U-34, and U-52—all plagued with mechanical difficulties—would have to be used with the greatest care. Only Kretschmer’s new VIIB, U-99, was in good enough condition to mount a patrol from Lorient and return to Lorient. The other three would have to patrol home to Germany, perhaps to sail no more to the Atlantic.
Rollmann in U-34 left first, on July 23. Capitalizing on B-dienst information, he intercepted inbound convoy Halifax 58 near Rockall Bank. Although some torpedoes malfunctioned or missed, he sank four ships for 29,300 tons, including the 10,400-ton British tanker. Thiara and the 9,300-ton British freighter Accra. Home-bound to Germany, he sank the 700-ton British submarine Spearfish off Norway with his last torpedo, and recovered one lucky survivor from the wreckage.
Dönitz was ecstatic. Those five sinkings, added to the eight on the outbound leg of U-34’s patrol in June, gave Rollmann a total bag of thirteen ships for (it was believed) 74,300 tons. Including prior successes, Rollmann had sunk twenty-four ships for 121,900 tons, elevating him to number-one U-boat “ace” in ships and tonnage. This achievement earned Rollmann a Ritterkreuz (the fifth such award to German submariners) and the full Berlin propaganda treatment. But it was the end for U-34. Hopelessly plagued with mechanical problems, U-34 was sent to the Baltic under a school skipper. Rollmann joined the training command.
Otto Kretschmer in U-99 sailed next. Hugging the coast of the British Isles, Kretschmer went up to North Channel and over a three-day period he sank four ships for 32,300 tons, including the 13,200-ton liner Auckland Star. In return, Kretschmer received another terrific pasting (fifty close depth charges) from escorts. Undamaged—and undeterred—he got on the trail of an outbound convoy and attacked three large tankers in ballast, firing one torpedo at each. Kretschmer claimed all three tankers had sunk—reporting seven ships sunk for 56,000 tons in a mere six days—but the tankers were only damaged. Although Dönitz knew from B-dienst that the claims were exaggerated, he liked Kretschmer’s aggressive style and, perhaps for propaganda purposes, upped Kretschmer’s bag to 65,137 tons, which gave him a total of 100,000 tons, qualifying him for a Ritterkreuz. When Kretschmer pulled into Lorient after a patrol of but twelve days—the shortest torpedo patrol on record—Raeder and Dönitz were standing on the dock to present the medal.*
Lemp in U-30 and Salmann in U-52 sailed last from Lorient. Homebound, Lemp sank two ships for 12,400 tons, but engine problems forced him to abort and go directly to Germany. Lemp’s confirmed bag, including Athenia, was sixteen sinkings for 80,232 tons—plus damage to the battleship Barham—deemed sufficient for a Ritterkreuz, which was awarded while U-30 was still at sea. Upon arrival in Germany, the boat was retired to the Baltic; Lemp and many of the U-30 crew were assigned to commission a new IXB. Homebound, Salmann in U-52 sank three British freighters for 17,100 tons and incurred heavy battle damage from a depth-charge attack, which kept the boat in the yards for the next four months.
By this time the eighteen surviving Type II and IIB ducks had been assigned to full-time duty at the burgeoning submarine school. The seven surviving Type IIC ducks of the Emsmann Flotilla (U-56 to U-62), basing in Bergen, patrolled in the Atlantic, terminating the short voyages in Bergen or Lorient. In nine patrols mounted in July off the heavily defended North Channel, the ducks sank twelve ships for 64,600 tons, including the 7,000-ton British tanker Scottish Minstrel. Otto Harms in U-56 sank the biggest vessel: the 17,000-ton British auxiliary cruiser Transylvania.
These duck patrols were useful for indoctrinating skippers and crews to combat, for diverting the enemy’s slim ASW forces away from the oceangoing boats, for spotting outbound convoys, and for creating fear and confusion by the occasional sinking in British home waters. But, owing to the crush of students at the submarine school, the OKM ruled that commencing on October 1, the ducks of the Emsmann Flotilla (U-56 to U-62) were to be assigned to the training command, together with most of the sixteen brand-new Type IID ducks (U-137 to U-152) and two Type HBs (U-120, U-121) originally intended for export. These diversions were to virtually close down duck patrols in British home waters.