Seizing the Enigma (20 page)

On the morning of Sunday, February 11, she headed south into the entrance of the North Channel, which divides northern Ireland from Scotland. The channel swarmed with ships, both illuminated and darkened; lighthouse beacons swept over the waters. As it grew light—around 9
A.M
. in those northern latitudes at that time of year—Dresky put the U-33 on the bottom in 200 feet of water. He planned to surface at darkness and to race at top speed as close as possible to the entrance to the Firth of Clyde, one of Britain’s busiest estuaries and the home of the nation’s most important shipbuilders. There he would again settle at daylight, surface at night to sow the mines the U-33 was carrying, and then get back to the open Atlantic before dawn.

It was cold and damp in the boat. The heating, not very strong in any case, was rarely turned on because it used up precious electricity. The sailors could see their breath when they spoke. Condensation ran down the bulkheads. But the men were well dressed. Their shoes had thick cork soles; they wore heavy underwear, and the elastic cuffs of their leather jackets and pants gripped wrists and ankles to retain body heat.

The day passed slowly. Little could be done for fear of making too much noise. Finally, night brought the tedious Sunday to a close, and Dresky put his plan into operation. On the surface of the black waters, visibility was about half a mile. Around 2
A.M
. of February 12, the U-33 Passed a huge shape, probably a heavy cruiser at anchor. The lookouts did not spot her. Below decks Schilling, the engineer, checked the machinery. Everything seemed
in Ordnung:
batteries at 161 volts at 30 degrees centigrade with 34 millimeters of acid. At 4 o’clock, he climbed to the conning tower. Dresky told him of the cruiser they had passed and said, almost as if it were a joke, that just now a destroyer was speeding toward them.

It was not a destroyer but a minesweeper, H.M.S.
Gleaner
, which had been on night patrol at the 15-mile-wide entrance to the Firth of
Clyde. Under instructions to watch along the 25-fathom contour, her captain, Lieutenant Commander Hugh P. Price of the Royal Navy, a hydrographer, sailed a right triangle, one apex of which was near the rocky islet Ailsa Craig, which rises abruptly 1,100 feet from the sea to a conical summit. At 2:50
A.M
., as the vessel was steaming on the due-south leg of the triangle, the seaman listening on the hydrophone reported hearing a strong sound from slightly off the
Gleaner
’s starboard bow. The officer on watch brought the 4-inch gun and the depth charges to the ready, altered course toward the object, which had moved to off the port bow at a range of almost 2 miles, and called Price.

On the bridge, Price heard strong hydrophone noises that sounded
tonk, tonk, tonk, tonk
at a rate of about two a second. He swung toward the moving object and increased speed to 16 knots. At 3:16 the range increased slightly, but thereafter it decreased. He swung his vessel to bring his searchlight to bear.

Aboard the U-boat, just after Schilling saw the shadow of the surface vessel, he and Dresky went below. “Prepare to dive” rang out. The U-33 submerged. A moment later Price, observing that the target bearing was rapidly drawing aft, had the searchlight switched on. He spotted something that looked white—possibly spray from the submarine—but it disappeared almost at once.

The light was seen aboard the U-boat, which had apparently then not gone entirely under. After she submerged totally, the crew heard each beat of the ship’s screw passing overhead from starboard stern to port bow. Price knew he was passing over the target, but trouble with the depth charges led him to wait until he could fire a pattern instead of dropping the charges haphazardly. In the submarine, Dresky ordered a dive to 125 feet, but the vessel had reached only 80 feet when the
Gleaner
, which had circled around and made contact again at 3:53, fired a pattern of four depth charges that exploded at 150 feet, not far from the U-33.

The detonations shook the U-boat. Its lights went out. With the booms, the crew members ducked their heads and hunched their
shoulders. The emergency lighting came on but could barely penetrate the dust, thick as fog, that the explosions had kicked up. None of the men screamed; no one cried; no one dirtied his pants. Their earlier attacks had toughened them, and their comradeship sustained them. From all parts of the vessel then came the reports of damage. The rudder and diving plane indicators had failed. All depth indicators were broken. There were two leaks. The starboard electric motor was sparking. The gauges of the rear electrical control panel were burned out. The gyro compass had reversed itself. A welded seam had torn. But all in all, the damage was not great. The crew began to replace the broken light bulbs. Dresky ordered the crew to put on their escape apparatus, then: “Absolute silence in the boat. Put her on the bottom!” And the U-33 settled to the sea floor. The men took off their shoes and spoke only in whispers.

On the
Gleaner
, the shock of the explosions briefly extinguished lights and caused her to lose contact with the submarine. The reloading party was having difficulty because the ship canted from side to side as Price turned her in giant figure 8’s to remain over the target. At 4:12 he fired another pattern. In the U-boat, extra machine parts were flung from their holders. More bulbs failed. Both diesel exhausts began to leak. Dresky asked Schilling what they should do; the engineer proposed trying to sneak away under water. When Schilling started the pumps to force water out of the ballast tanks to increase buoyancy, however, Dresky ordered them stopped because they made too much noise. But the submarine, with 2 tons of negative buoyancy, could not free herself from the bottom by her propellers alone.

At around 4:40, the
Gleaner
approached for another attack. Schilling started the pumps, apparently thinking there was little to lose, but Dresky canceled the order. Five more depth charges rocked the submarine. The men remained unshaken. Lieutenant Johannes Becker, the second watch officer, sipped a beer in the torpedo room. “Water coming in!” was reported from astern. Rottmann went back to investigate. In the diesel room, the machinists were sitting on the equipment so
their feet would not get cold. They looked at Rottmann’s face when he came in to get a clue as to the condition of the boat. He put on a neutral expression so as not to frighten them. He need not have worried. Many seemed to have the same feeling that Machinist Ernst Masanek had about himself: “Don’t worry. You’ll get out of it all right.” Rottmann reported that only a connection between two internal tanks had been torn and that water was running into the bilges.

Dresky then ordered Schilling to get the submarine off the bottom. There was no point in awaiting the next attack and the next and the next. But once the submarine was moving, then what? The man at the helm said that escape was not possible, that all they could do was save the crew. Schilling pointed out that traveling submerged in those narrow and shallow waters, which were streaming at 6 knots, was extraordinarily difficult. Dresky agreed and concluded that surface travel offered the best chance of escaping. He began preparing for this, ordering the first watch officer to ready the mines for discharge and the second watch officer, Becker, to prepare the secret materials for destruction.

The most secret item was the Enigma cipher machine. Becker knew that the rotors were its heart and that the machine, if recovered by the British, would have little value without them. So he took the three in the machine and the five others in their wooden box and distributed them among a few crew members, including Rottmann, Lieutenant Karl Vietor, and Machinist First Class Fritz Kumpf. He instructed them to drop the rotors into the sea as soon as they went overboard. Meanwhile the crew members prepared themselves for immersion in the frigid water by dressing in as many layers of clothing as possible. This would tend to hold the water that was warmed by their bodies near them and prevent their being chilled by cold water flushing past their skin. Rottmann put on, over his underwear, his pullover and service trousers, a coverall, a leather jacket, leather pants, fur pants, and his escape apparatus.

The effort to lift the vessel began. With two-thirds of the compressed air supply gone, Dresky ordered the unorthodox maneuver of
blowing the water out of one of the torpedo tanks, then, “Surface!” and “Air in all tanks!”

A few moments later, the submarine breached. At 5:22 she was caught in the glare of the
Gleaner
’s searchlight but then was lost when the light failed, owing to broken arc carbons. Price substituted the 10-inch signaling lamps and spotted the U-boat again. The
Gleaner
fired five rounds from the 4-inch gun and turned to ram. Dresky, who had emerged onto the conning tower, saw that the British ship was only a few hundred yards away and shouted down into his boat: “Abandon ship! Blow her up! Report [the situation] by radio!” Schilling shouted that the diesel engines were still working, but Dresky repeated his order. As the crew members clambered out, Schilling opened the main induction flappers, heard with satisfaction the crackle of the fuse for the scuttling charge, and opened the vents of torpedo tubes 1 and 2. But he could open the latter’s vent only part way. Someone called to him from above. He went to the conning tower and reported what was going on to Dresky, who came down, tried to open the vent of tube 2 without much success, and soon climbed back up. Schilling then went to the rear control room and opened both outboard valves until a heavy stream of water flowed over his feet. Satisfied, he went out, noticing that the main vent valves in the main control room were already under water.

On the surface, Price saw the crew tumbling out of the U-33 holding up their hands in surrender, so he had the wheel put hard to starboard and all engines put full astern. The
Gleaner
stopped parallel to the U-boat about 200 yards away. Suddenly a shower of sparks erupted from the conning tower: the explosive had apparently set off some signal rockets and some of the smaller munitions; the heavier munitions were already flooded. The crew abandoned the submarine, which almost immediately sank by the bow at an angle of 40 degrees.

As the stern disappeared, Dresky led the floating men in three cheers for the U-33. It was 5:30
A.M
.

The water was bitter cold and choppy; the night was black. Rottmann pulled his three rotors from his pocket and let them sink
into the sea. Vietor did the same with his two. Dresky ordered, “Stay together as much as possible.” Schilling, swimming in a large group of crew members, was often asked whether they would be rescued. As the minutes and quarter hours passed, he repeatedly told the men “They’re on the way. Stick it out and keep swimming.” His pod kept getting smaller as men vanished. Meanwhile the
Gleaner
had lowered boats and moved slowly into the center of the largest group of survivors. Suddenly Schilling saw a searchlight nearby and then the side of a ship and a manila line, to which he clung before losing consciousness. He and the others had been in the water almost two hours. Only the many layers of their clothing had saved them. The
Gleaner
and other vessels picked up four officers and seventeen men. Dresky did not survive, and his body was never recovered. He had met his doom.

Rottmann was picked up by a cutter, which took him to the
Gleaner
. He passed out, then woke up in a bathtub filled with warm water. The bearded Royal Navy ensign who was guarding him gave him pants and shoes. They spoke in German, and Rottmann asked whether he could visit his crew to see who was alive. The officer took him to a room in which a clump of men was sitting on the deck, each with a blanket, and shivering. On seeing Rottmann, Kumpf, the seaman who had been given three rotors to drop into the water, said,
“Herr Oberleutnant!”
and tried to rise to report in a proper way. But Rottmann put his hand on his shoulder and told him to stay down.

“Herr Oberleutnant,”
Kumpf resumed, “I forgot to throw the wheels away.” Rottmann went over to the bulkhead where Kumpf’s leather pants were hanging in the hope of finding the rotors so he could himself surreptitiously get rid of them. He squeezed the pants. They were empty. The British had gotten the wired codewheels.

T
HE ROTORS THAT SOME ALERT
B
RITISH SAILOR HAD REMOVED
from Kumpf’s leather pants went to Bletchley. Two turned out to be hitherto unknown naval rotors: VI and VII. Though in theory their wiring could have been reconstructed, their capture speeded the work of the Hut 8 cryptanalysts. Later they obtained rotor VIII from another naval capture. But even possession of a full set of rotors, together with a copy of the regulations for the use of the naval Enigma recovered from the U-13 in June 1940, did not make possible regular, or even frequent, solution of German naval cryptograms. And the U-boat war was increasing in intensity.