Michael Dobbs - Saboteurs

As they lay in their bunks that first night, Dasch and the other saboteurs tried to adapt to the strange sensations of life aboard a U-boat. Sleep was practically impossible. They already felt seasick from the violent rocking of the boat back and forth on the waves. And then there was the constant din from the two 1,160-horsepower diesel engines, known affectionately to the crew as Max and Moritz, in the stern of the ship. The diesels made a gurgling sound as they sucked in air from a pipe mounted in the bridge.

At dawn, the U-boat dived to avoid being spotted by the Allied planes constantly patrolling the Bay of Biscay in a circular loop from their bases in Cornwall, on the southwest tip of England. When the ship was below the surface, everything seemed much more peaceful to the saboteurs huddled in their bunks. The roar of the diesels was replaced by the hum of the battery-powered motors. The violent rocking and shaking subsided, and it was as if the submarine were floating gently through space.

For the first two days, the crewmen were told nothing about their new passengers. On the third day out of Brest, Linder finally made an announcement over the loudspeakers, his voice echoing from the forward torpedo room to the engine room in the stern. He informed the crew that their four guests were undertaking a “special assignment” to America. 8The crew members were to treat the visitors well, refrain from asking questions, and observe strict secrecy on pain of death.

AS U-202 was leaving Lorient harbor, a battle of wits was under way on the grounds of a rambling English manor house that would eventually determine the outcome of the Battle of the Atlantic. Hundreds of cryptanalysts were attempting to unscramble the latest batch of top-secret telegrams from the German High Command to military and naval units all over Europe and North Africa. Bulky machines known as “bombes” spun their rotors to discover the precise match of letters and numbers that would break the German code.

Crude precursors of the computer, the bombes were meant to simulate the operation of the Enigma machine, the supposedly unbreakable cipher system used by the German army and navy for their daily communications. Breaking the German code was somewhat like solving a vast jigsaw puzzle while blindfolded: a combination of inspired guesswork and trying every single logical possibility. What made the process even more mind-numbing was that the Germans kept rescrambling the puzzle.

By late 1941, the code breakers of Bletchley Park had developed a system that allowed them to read secret German messages within a few hours of receiving them. By dint of analytical brilliance, a captured German codebook, and mechanical force, they gained priceless insights into Hitler’s plans and intentions, which they passed on to British Prime Minister Winston Churchill and other wartime commanders. The code-breaking operation opened up intelligence on a vast range of subjects, from Hitler’s decision to invade the Soviet Union in the summer of 1941 to Luftwaffe raids on Britain to the mass murder of Jews in Nazi-occupied territories. British commanders were also able to use the decrypted messages to plot the movements of German U-boats around the Atlantic, and order Allied convoys to make adjustments in course to steer clear of the submarine menace.

At the beginning of February 1942, disaster struck. Suspicious of Allied successes in evading his U-boats, Admiral Dönitz ordered the installation of a new, and even more complicated, cipher system on board the submarines. By adding a fourth rotor to the three-rotor Enigma machines, he increased by a factor of twenty-six the number of possible letter combinations available to German cipher clerks. 9What had become a manageable deciphering operation was now beyond the capabilities of even the cryptological geniuses of Bletchley Park, at least until they succeeded in building faster and more powerful code-breaking machines. Almost overnight, the task of tracking down Dönitz’s U-boats became far more difficult.

There were still some small windows into the movements of U-boats, however. One was a network of radio direction finders built by the Americans and the British, which detected the emission of radio signals from submarines. By triangulating the data from several direction finders, Allied intelligence officers were able to plot the location of a U-boat with considerable accuracy, particularly along the coast. The system was not much help in predicting where the U-boats would move next, or where they were when they maintained radio silence, but at least it gave the Allies a sense of the maritime battlefield. A second window was provided by messages from support ships, not all of which had made the transition from three-rotor to four-rotor Enigma machines.

By decrypting messages from the commander of the seventh German naval flotilla to U-boat escort ships, Bletchley Park was able to track the departure of U-584 and U-202 from Lorient at the end of May. 10The information was immediately transmitted to the Submarine Tracking Room in the British Admiralty in London, where it was plotted on a giant wall map. Messages were sent to the Royal Air Force to watch out for German U-boats in the Bay of Biscay.

But the mission of the two U-boats remained a closely guarded secret from Allied intelligence, as did the presence on board of eight Nazi saboteurs.

A DAY after U-584 left Lorient with Kerling’s party, a lookout spotted a dot on the horizon, soon after the submarine came to the surface. “Alarm!” he yelled into the intercom connecting the bridge to the control room below. “Enemy plane!”

From down below came the command “Flood!” There was a loud gurgling sound, as water rushed into the buoyancy tanks, expelling the air that kept the boat afloat. Within seconds, the watch officer and three lookouts had scrambled down the ladder that connected the bridge to the control room through the conning tower.

The plane had seen them as well, and was heading in their direction. “All hands forward!” yelled the captain, sending crew members slipping and sliding toward the forward torpedo room. As the bow of the boat tipped forward, dirty pots and plates scattered around the galley, and crates of vegetables slithered into the gangway. The U-boat was already several hundred feet down by the time depth charges began to explode in the water above. 11

With the exception of the V-men, everybody on board had a specific job. One crew member turned a valve to flood the ballast tanks, and send the boat plummeting downward. A second was responsible for closing the hatches. A third ensured that the ship was properly balanced. And all the time, the captain and chief engineer were relaying information and barking out commands over the loudspeakers.

“Eighty meters.”

“Sounding.”

“Twenty-two hundred in compartment one.”

“One hundred meters.”

“Eighteen hundred in two.”

The saboteurs sat huddled in their bunks, seasick and frightened, wondering how much longer they had to live. They counted the depth charges exploding around them, battering the boat as if it were a tin can.

Three.

Four.

Another huge explosion.

Six.

Seven.

Eight.

The last explosion was followed by a prolonged silence. Some of the crewmen broke out in grins: the worst was evidently over. They were out of range of the depth charges. The plane had given them a fright but had failed to score a direct hit, and their ship was undamaged.

The saboteurs on U-202 were spared such drama, but they quickly understood that the sea around them was alive with danger. Linder instituted daily diving drills, practicing every conceivable kind of dive: fast, slow, deep, shallow. At the end of each practice session, the captain would announce, “Alert over, dive for exercise only.” 12Until the dive was over, Dasch and the others never knew whether an alert was for real or for practice.