Tidal Rip

to Luanda, along here, the massed U-boats will come down and try to savage their left flank.” Jeffrey gestured at the chart with his hands. The Angola Basin abutted the middle of the north-south part of the African coast, and ran up to the outlet of the Congo River itself. “Other U-boats are probably lurking southeast of us somewhere, basing out of South Africa, to squeeze the convoy’s right flank.” He gestured again at the bottom part of the map.

As if for emphasis, another nuclear blast went off in the distance. Jeffrey looked at the sonar speakers. Every one of those detonations sours possible Allied success. The ocean ecology and food chain here are hurting. At least prevailing winds and currents carry the fallout away from land.

“Sir,” Sessions asked, “what about the two-hundred-mile limit?”

“Yes, I was coming to that.” Jeffrey pointed at the blue — friendly — chunk of Central Africa. “For better or worse, the Allied pocket’s share of the coast is just about four hundred miles. We can only hope the Axis keep to their own rules of engagement, to not use atomic weapons within two hundred miles of U.S.-held turf.” He spoke to the assistant navigator, and green arcs marked the outer edge of this hoped-for safety zone against Axis nukes.

“Sir,” Bell said, “based on what we just went through in South America, I’m not sure how much we can count on Axis ROEs.”

“Agreed.”

“There’s also the broader matter of the Axis land offensive,” Milgrom said. “The pocket’s coast may get pinched off. The convoy’s landing might have to be an amphibious combat assault. The losses would be heavy, even against conventional arms.”

“I know.”

“The danger,” Sessions said, “is that since the nuclear shooting has started at sea, and the U-boats are in hot pursuit of our surface ships, the atomic combat may run on momentum unbroken, straight through the two- hundred-mile limit and onto the land.”

Jeffrey nodded. “A paramount Axis strategic goal is the German and Boer armies in Africa linking up at all costs. After what just did and didn’t happen in South America, we can’t tell what volatile mood Berlin and Johannesburg are in right now. There are some pretty scary wild cards here. They all emphasize the vital importance of Challenger’s mission. Sink the von Scheer… My concept of operations against the von Scheer is very simple. Before that, are there any questions on what we’ve covered so far?”

There weren’t.

“Assistant Nav, plot the great circle route from the Tristan da Cunha Island group to the Congo River outlet.” Once more the senior chief typed — a great circle route meant the shortest distance between two points on the globe. Another red line came on the screen.

“As you all can see, the von Scheer’s quickest final approach from South America to the convoy and the pocket lies exactly along the Walvis Ridge. The Angola Basin on one side and Cape Basin on the other both are deeper in most places than our and the von Scheer’s crush depth. For example, eighteen thousand feet along here, and here.” Jeffrey touched spots on the chart. “The Walvis Ridge itself is an underwater mountain range that rises one to three miles off the surrounding ocean floor. In a few spots seamount peaks almost reach the surface. Questions?”

No one spoke.

“As Sonar told us two days ago, the deep sound channel functions perfectly in either basin. Active and passive detection and counterdetection ranges there would be long. The Angola Basin is heavily bathed in sound. So is the Cape Basin, less so, by SSQ-Seventy-fives presumably dropped on Norfolk’s orders in our support. These sounds give the basin waters good acoustic illumination for ambient and hole-in-ocean sonar search modes. You all know what that means, tactically.”

“Whichever of us sticks our nose out of the Walvis first,” Bell said, “von Scheer or Challenger, can be seen by the other vessel while still in good hiding terrain in the ridge. The guy who’s hiding gets off the first shots, and wins.”

“Correct,” Jeffrey said. “So we’ll use that. Ernst Beck has to work his way along while hugging the ridge, and he doesn’t have forever. He has to get in position to fire his missiles while the convoy is still out at sea. Once it reaches harbors or good beaches and unloads, him sinking cargo ships and troop transports is a somewhat hollow victory. The carrier groups would be freed to concentrate on self-defense and their own mobility, and they’d be much harder for him to hit as well.”

“So what’s the plan, Skipper?”

Jeffrey touched the own-ship icon on the navigation chart. “At the moment we’re in the foothills approaching the Wust Seamount, on a base course zero four five.” Heading northeast. “Just beyond that seamount is a sort of mountain pass through the Walvis, where the ridge terrain is broken by a flat path leading north-south. That path is very deep, right around fifteen thousand feet, about as much as I want our hull to have to take. But this mountain pass, if we can call it that, has a wide-open view to the north and the south.” The pass was a few miles long, the same way the prominent ridge terrain was a few miles wide from north to south.

“Everyone, back to our stations. Let’s get to work.”

Jeffrey studied the gravimeter. Then he hardened his voice. A jagged, very steep, extinct volcanic pinnacle soared up close by the ship to starboard. “Helm, maintain nap of seafloor cruise mode. Come right and hug the east face of the Wust Seamount.” He touched his console screen with his light pen — the mark repeated on Meltzer’s displays, relayed through Challenger’s data-distribution network. “At this designated way point, Helm, all stop. Then rise on autohover, make your depth three thousand feet.”

Meltzer acknowledged. Challenger banked into a gentle turn to starboard.

Jeffrey called up his weapons-status page. “Fire Control, pull the Mark Eighty-eights from tubes five and six and replace with high-explosive Mark Forty-eight Improved ADCAPs.”

Bell relayed commands. “Sir, why ADCAPs? Their punch is weak and their crush depth is shallow.”

“Two reasons, Fire Control. In this ridge terrain, first-detection and engagement ranges might be very short. We need the option to shoot without a self-kill from our own atomic warheads. Hence the high-explosive fish. And the von Scheer needs to go shallow to launch her missiles.” Jeffrey glanced at the photo of Ernst Beck he still kept windowed on his console. “That’s Beck’s Achilles’ heel. Shallow, we can use ADCAPs.”

“Understood, sir.”

Meltzer reported he’d reached Jeffrey’s designated way point.

Jeffrey eyed a depth gauge and the gravimeter. Challenger began to rise, on a level keel and with no forward speed.

“Fire Control, pull the Mark Eighty-eights from tubes seven and eight. Replace with Long Term Mine Reconnaissance System units.” The LMRSs were unmanned undersea vehicles — remote-controlled off-board probes; they could be fitted with various specialized black boxes. “Missionconfigurable load-out is to be modules for antisubmarine passive sonar. I intend to use them as early-warning detection aids against the von Scheer. For stealth, control both units by fiber-optic tether.” The probes could use an acoustic link instead, but the digital bursts might be heard by a sophisticated enemy.

“Understood, aye aye,” Bell said.

Jeffrey watched his weapons-status screen. The color coding for tubes five through eight changed from green — ready to fire — to red: not ready. Then tubes five through eight had their outer doors closed and the seawater drained. The inner-tube-door icons popped open. The Mark 88s were disarmed by the torpedo-room crew, and pulled from the tubes and placed on the storage racks by the hydraulic autoloader mechanisms. ADCAPs, and off- board probes, were presented to the tube breach doors. The new units slid into the tubes, and the inner breach doors closed.

“Sir,” Meltzer said, “my depth is three thousand feet.”

“Very well, Helm. Fire Control, make tubes seven and eight ready in all respects including opening outer doors.”

Bell acknowledged. He relayed orders to flood and equalize the pressure in the tubes. The outer doors slid open.