Cauldron

A sudden, high-pitched wail stopped him in midsentence, rising and falling in a steady rhythm.

“What’s that noise?” Alarm flashed across the reporter’s face as he recognized the base air raid siren. Still looking into the camera, he stammered, “Is this some kind of drill?” He turned to his left and repeated the question.

The view shifted, showing an ashen-faced RAF lieutenant motioning frantically toward the ground. “Take cover! Take cover!”

Explosions drowned out the siren.

The camera image jarred, then tumbled to lie on its side, showing a cluster of buildings — aircraft hangars and living quarters. A mike picked up shocked voices in the background. “Are you all right?… Jesus, look at that! Where’s the camera?”

The image spun and shook, then steadied on a transformed scene. A pall of smoke hung over the flight line, fed by masses of flames below it. The fires dwarfed everything in sight — solid sheets of flame that towered over the trucks and men scrambling to control them.

Shaking again, the CNN cameraman panned left, then right, unable to capture the scope of this disaster in a single frame. The long, ordered lines of soldiers were gone, replaced by screaming clumps of wounded men and silent heaps of those who were dead. Secondary explosions threw mangled pieces of aircraft into the air as balls of orange-red flame mushroomed in the mass of wreckage.

IN THE THAMES ESTUARY

The German submarine commanded by Captain Theodor Ritter lay bottomed on the Thames Estuary, practically hugging an old wreck left over from the last war. She was just forty kilometers east of London.

German submarines have never had names. This one was no exception. She was simply called U-32, the “U” standing for Unterseeboot, undersea boat. She was small, only one-fifth the size of a Los Angeles-class nuclear sub. Unlike America’s SSNs, Germany’s U-boats didn’t need a cruising range measured in tens of thousands of miles. They were built for coastal operations, close to their home ports.

As a Type 212 boat, U-32 was also brand-new, and new technology gave her an edge over the enemy. Instead of a large, expensive nuclear reactor, she carried an “air-independent” propulsion plant. When their electric batteries ran low, older conventional submarines had to snorkel — drawing air from the surface for their diesel engines. But snorkeling makes noise, and making noise during wartime is a sure and certain way for a submarine to get itself killed.

U-32 and the other boats in her class didn’t have to snorkel. Instead, a tank of liquid oxygen supplied an advanced engine, which replaced the diesel. That meant they could charge their batteries while submerged, and then proceed silently on electric motors. The combination of ultraquiet propulsion, a small, nonmagnetic hull shaped to help scatter sonar echoes, and a first-rate sonar and fire control system made U-32 and her sisters deadly opponents.

Slipping this far through the Combined Forces ASW patrols had been difficult, but the German sub wasn’t looking for a fight.

U-32’s submerged mobility, almost as good as a nuclear boat’s, had let her sidestep or backtrack if she found herself near a prowling adversary. Her skipper and crew knew there would be time to deal with isolated enemy destroyers or frigates on the way out.

Besides, the war was almost three weeks old now. Patterns had begun to emerge in the way the Americans and British patrolled — patterns that could be exploited.

So now U-32 lay motionless in the mud. With her motors and even her air recirculation pumps shut down, she would be almost impossible to hear on passive sonar. Even normal active sonars couldn’t find her this close to the bottom — the mud and sediments blurred sound waves bouncing off it.

But the Royal Navy was used to operating in shallow water. Many of its ships carried special high-frequency sonars that could provide almost picture-quality images of whatever lay on the bottom.

The German submarine was relying on three things to safeguard her from such sonars. First, her small size — barely one thousand tons surfaced — and minimal sonar cross section. Second, her anechoic coating and special hull design should help absorb and scatter enemy sonar pulses. Last, and most important of all, U-32 lay close beside the old wreck, almost hull-to-hull — hiding in the sonar and magnetic shadow cast by the larger vessel.

Ritter and his crew resigned themselves to a long stay on the bottom, breathing air that would grow fouler as the hours passed. Like a spider in its web, the U-32 lay in wait for her prey.

HMS Brecon led the outbound convoy heading for Gdansk. Built with a glass- reinforced plastic hull, and equipped with a pair of unmanned submersibles and a high-frequency sonar, the Hunt-class minehunter had proven her worth after the Falklands war by sweeping Argentine minefields laid off Port Stanley.

Now she plodded down the estuary at a sedate ten knots, sweeping back and forth. Behind her came two Type 22-class frigates, HMS Chatham and HMS London.

Three merchant ships followed the warships. A third frigate, HMS Argyll, a Type 23, brought up the rear.

Every warship was at action stations, expecting trouble. The three merchant ships, one bulk freighter and two container ships, held the better part of a British armored regiment, along with spare parts and ammunition.

U-32’s crew, lazing at their own duty stations, sat up as the first chirp of the enemy’s sonar beams came over the attack center speaker.

Ritter cocked his head toward the ceiling, listening as the British ships steaming overhead came closer.

The high-frequency chirping swelled, backed by the low, dull thrum of the minehunter’s engines. New sounds over the speaker signaled another British ship moving in behind the first.

Chatham’s active sonar made a deeper, duller noise than Brecon’s set.

More crewmen tensed as the sounds grew steadily louder. In theory, they were reasonably safe from detection. But theory seemed a poor substitute for certainty when the sonar pulses lashing the U-32 could be heard pinging through the hull itself.

Aboard Brecon, the senior petty officer manning the high-frequency sonar watched his screen carefully. He knew these waters well. The wreck, a coastal freighter sunk by Stukas in 1940, was a familiar landmark on his charts. He glanced at the digital clock above his display. They were right on time.

The wreck appeared, crawling down the screen as Brecon steamed toward it. He studied the bottom area around the sunken freighter closely. Nothing. Just the usual jumble of green-white shapes. Anything shaped like a submarine should have stood out clearly.

U-32’s sensitive sonar gear picked up machinery sounds emanating from the oncoming convoy and fed them to her fire control computers. By comparing the noises against prerecorded data sets, the computers were able to rapidly classify each ship. As always, information obtained during peacetime exercises was proving useful in war.

Ritter hovered over the computer display, watching the results of this automated search appear. Moving blips indicated seven ships sailing east in line, centered in the channel. His fingers drummed against the console. The three warships were tempting targets, but his instructions were clear. The merchantmen were his first priority.

“Prepare for an attack,” he ordered. “Two torpedoes at the lead merchant, three each at the other two.”

Every man in the boat held his breath as the ships drew nearer. The swishing roar of the enemy minehunter’s screws passed overhead and began to fade.

Ritter kept his eyes on the display, watching the six ships behind Brecon.

Bearing, still steady. Range, decreasing. He looked up at his diving officer. “Lift off.”

Valves opened, and a shot of compressed air entered U-32’s ballast tanks, changing her buoyancy from slightly negative to slightly positive. She lifted smoothly off the bottom. At the same time, her silent propellers spun up slowly, giving the submarine bare steerageway.