U-121 had turned rapidly and was retracing her steps. The noise of the destroyer's propellers died away. Her men could still hear the swish of the asdic's whip, but it reached them only through the disturbed water of the explosion. Soon even this was lost to unaided ears; only Braun, the hydrophone operator, with his delicate instruments could hear the transmissions from the British ship.
"Half ahead, four knots," the Kapitan ordered when fifteen minutes had passed. "Steer one-two-oh."
The whirr of the motors eased. The boat stole stealthily forward, suspended in a dim world above one that was darker yet — and cold as death.
Braun called the control room on his voice pipe. "Herr Kapitan, the British transmissions have stopped and I have heard fast but distant propellers. They are going away, Herr Kapitan."
Von Stolberg thought quickly. It seemed indeed as if he had been successful in shaking off the enemy. But why had the destroyer suddenly moved away? Either the British Captain was working some scheme of his own or something might have occurred up in the sun and air above that had drawn him off. Could it be that the Cecilie, cruising in the area, had unwittingly come across the destroyer? The armed German raider could certainly sink the destroyer, but she would never catch her if the latter decided to keep out of range and wireless the Admiralty for assistance.
"Time to turn to course two-one-oh, Herr Kapitan." It was the navigator speaking.
"Very well."
But was it "very well"? If he kept on his present course, toward the southeast, the chances of being found were very remote indeed. Even if the destroyer did come down that way, he would hear the transmission of her asdic long before she was close enough to detect an echo, and he would be able to avoid her. Would honor be satisfied if he steered southeast until dusk and then surfaced to go on to the rendezvous on his Diesels? If he adopted that course, he thought he could just make it in time. But it would be very very tight, and he would have nothing to spare if anything were to go wrong.
"Very well, Herr Oberleutnant. Steer two-one-oh." His mouth was compressed. To make the rendezvous was vital, both to his personal honor and to the success of the Fatherland — for the prize was colossal. He could get the photocopies of the precious ciphers to the High Command at least fourteen days earlier than the originals brought back by the Cecilie. Ahead of the surface ship lay a long, dangerous and circuitous route. She would be forced to dodge backward and forward, for when sighted by another ship she must pretend to be a fast merchantman sailing independently between the American continent and the British Isles. It would be at least five weeks before she could hope to make Bremen. He, von Stolberg, could deliver these invaluable documents in three weeks.
The Kapitan bent his face to the voice pipe that led to the hydrophone cabinet. "Braun, can you hear anything?"
"Nothing, Herr Kapitan."
What could the Britisher be up to? He was very tempted to go to periscope depth and take a look round. If the enemy had gone, he was quite safe. If the destroyer should return at anything like the speed at which it had left, then the hydrophone would detect it when it was at least four miles away.
He gave the order and watched the needle of the depth gauge rise quickly. Once more the periscope rose smoothly from its well. Instinctively the Kapitan carried out the antiaircraft search that years of training under North Atlantic conditions had laid down as the first protective glance on surfacing.
But neither in the sky above nor on the surface could he see anything. The thought crossed the Kapitan's mind that he might surface and try to run away on the Diesels. At best such a course might lead to his escape; at worst, even if the destroyer returned, he would have had some chance to recharge the batteries and refresh the air in the boat.
"Prepare to surface."
"Herr Kapitan, Herr Kapitan!" It was Braun's voice from the hydrophone cabinet.
"Find out what it is, Otto." His eyes were still glued to the periscope.
"Herr Kapitan, Braun reports high-speed propellers, distant, getting nearer."
The Kapitan left the periscope and pushed past von Holem to the tube. "How fast, Braun, and what bearing?"
"Very fast indeed, Herr Kapitan, on the starboard beam."
Back at the periscope. Von Stolberg swung it round to the starboard bearing. In the center of the horizon two white plumes of water were visible. Between them swayed the destroyer's delicate mast and pale-gray upperworks. It was useless to try to fire torpedoes at a destroyer traveling at that speed. Angrily he pushed the button that sent the periscope down into its well.
"Emergency dive to eighty meters."
The boat dipped steeply by the bow, and the engine hum increased. Schwachofer was flooding the forward tanks first in order to increase the angle of dive and send her hurtling into the depths. The valves would be shut off in turn so that she would steady up on an equal keel. The officer was — and had to be — an artist at catching her in her dizzy plunge downward; one false move on his part and she would go on down to a depth that would crush even her strong hull.
With one hand grasping the now-housed periscope to steady himself, von Stolberg swore softly to himself. How the devil could you fight a madman like this Englishman?
"Can you hear any asdic transmissions?" he asked Braun.
"No, Herr Kapitan."
That seemed reasonable, for what he knew of the Allied asdic assured him that it could not be used above certain speeds. What then was in the British Captain's mind?
The boat was leveling off, and her motors were eased back to give her four knots now that they had driven her down.
"Silent routine," he gave the order. This would put the hydroplanes, which like horizontal rudders controlled her depth, into hand control, so that the motors that worked them at other times would not add to the noise.
All in the boat could now hear the drumming of the destroyer's propellers, ever growing in volume. Louder and louder it grew, until the ear, accustomed to the continually increasing racket, was shocked to hear the noise decreasing. Could she have passed beyond them and be going away? The noise still came from the starboard beam, but it was fading.
And then, with a crack that made even the most hardened and experienced stiffen, the asdic's lash fell on the iron shell that contained them. An agonized whisper swept through the boat as the men simultaneously released their breaths.
Du lieber Gott, the Kapitan thought. On my quarter at four hundred meters. If he attacks now, he has a chance to sink me.
"Hard astarboard — full ahead. Steer two-eight-oh." If I pass under him, show him my stern, he may not have time to prepare his attack.
The beat of propellers sounded overhead. His men instinctively bent their heads. Seconds ticked by. Then came the rumbling note of a depth charge — near enough in all conscience. If only it was no worse.
But it was! The Hecate's starboard throwers had hurled two charges fifty yards to one side of her track. The heavy one, sinking more quickly than the light one, exploded beneath the U-boat. The light one exploded above her, and the shock wave between the two was appalling in intensity. It felt as if the boat had been picked up by a giant hand and thrown upon a concrete floor. Every single thing in her was flung up and down by the repeated waves. The lights went out, and in the semidarkness the emergency lights, no bigger than flashlight bulbs, cast an eerie glow. The floor was littered with tiny fragments of shattered glass. A frostlike mantle was all that remained of the glass fronts on the hundreds of dials in the control room.