“Two tons of gold,” Fan breathed. “To buy what?”
“That’s exactly what worried us. What worried Churchill. We always knew that the German High Command might use the naval Enigma for purposes other than basic U-boat movement orders. Ever since the Japanese entered the war sixteen months ago, we’ve been keeping an eagle eye out for intercepts that might suggest covert supply arrangements between them and the Germans. The Germans are running out of basic raw materials, especially low-volume, high-grade metals and compounds that might be carried in useful quantities even in a submarine, and the Japanese want materials of their own. With surface shipment being impossible because of our control of the sea lanes, long-range U-boats are the only option. About two months ago, a US naval analyst in Washington linked an Ultra intercept to reports from agents in Tokyo that a special shipment had been requested. The material was radioactive uranium. That’s the real reason why those two American officers joined us six weeks ago. They want to be here in case we catch any similar intercepts. The Americans have been involved in a top-secret project to use uranium to make some kind of catastrophic bomb, and the idea that the Germans and the Japanese might be embarked on the same kind of project has put the fear of God into everyone involved.”
“Including Churchill,” Fan said.
“Especially Churchill. When he said the war will be won or lost in the Atlantic, he wasn’t just thinking of our merchant ships. He was also thinking of what might break through our defensive screen and reach the U-boat bases at Brest and Lorient. Despite the best efforts of our ships and aircraft, it’s still feasible for a U-boat on a long-distance voyage from Japan to reach Nazi-controlled territory undetected, recharging its batteries at night and refuelling from tanker U-boats on the way. The same goes in the other direction.”
Fan stared at the files, speaking slowly. “You need me because any operation to take out these U-boats or Japanese subs would be based on Ultra intercepts, and would therefore have to be factored into the calculus that’s my speciality. Act on too many intercepts and the Germans will become suspicious. And on the day when one of these special intercepts is acted on, Ultra intelligence related to other U-boat movements would have to be ignored and no convoys saved. Days like today?”
“Correct. We knew you were the right person for the job. Quick assessments will need to be made. You’ll continue to do your routine job as part of the operational intelligence team within the hut, the job you have been doing today, but any time one of these special intercepts is detected you will also be wearing this other hat, unknown to most of the others.”
“When you said our sub was in position, you meant to intercept U-515.”
“No. I meant to intercept convoy TS-37.”
“To intercept the convoy. Now I really don’t understand.”
“A long-range U-boat is due along that coast in a few days’ time. We know this because an Ultra decrypt a week ago showed that a tanker U-boat was heading to a refuelling rendezvous far to the south of the known operational schedules of any other U-boats currently in the Atlantic, including U-515. Our sub off Sierra Leone is one of two off the West African coast hoping to intercept the long-range U-boat when further decrypts pinpoint her position. But meanwhile, something else has cropped up. One of the ships in convoy TS-37 is carrying something we do not want to fall into enemy hands. Open up the cargo manifest for Clan Macpherson.”
She shuffled through the papers in the TS-37 file and found it. “Pig iron, hemp, general cargo from India. Pig iron is presumably code for manganese. Ah. It’s penciled in at the bottom, to be picked up in Durban. A consignment of gold bullion.”
“A very big consignment. We’ve secretly shipped as much gold as we can from South Africa since the outbreak of war. We need it to build up our reserves, and to fund the resistance in Europe. A consignment of this size would also be enough for the Germans to pay the Japanese for what the Nazi scientists want above all else at the moment: a cargo of uranium ore. The Japanese have opened up a new mine and apparently have a surfeit.”
“But how could the gold possibly fall into German hands?”
“Because the German High Command has ordered U-515 not to sink Clan Macpherson, but to capture it. We know that from an Enigma intercept. Despite our best efforts to keep all gold shipments out of South Africa secret, we believe that the Nazi agents in Durban must have caught wind of this one and passed the information up the line. They’re the ones we’re bluffing by relabeling manganese as pig iron. There is a reason why we haven’t shut them down, but that’s no concern of ours for now. What we also learned after the ship had sailed is that there are Japanese-trained operatives from the Indian National Army planted among the Lascar ratings in the crew of Clan Macpherson who are there to take it over once U-515 begins attacking the convoy, and who will then cause her to fall behind so the U-boat can come alongside. If the U-boat causes enough destruction in the main body of the convoy, then that’s where the escorts will concentrate, leaving stragglers to their fate. We know it’s a weak escort, and so do the Germans. We believe that the plan is then for U-515 to rendezvous with the long-range U-boat at a secret location to transfer the gold aboard. An audacious plan, but ingenious. And we have to do anything we can to stop it. I mean, anything.”
Fan suddenly felt sick. “My God. Now I understand what Johnson was saying. Our sub is there to sink one of our own ships. To sink Clan Macpherson.”
“That’s the real reason I snapped at him. He’s one of two cryptographers we brought in on this secret and assigned to spotting the special intercepts. We’d known about the long-distance U-boat program from agents in Japan, but it was Johnson who took that decrypt spotted by the US analyst and put it alongside a number of anomalous movement orders we’d decrypted over the past few months, ones that don’t mention a U-boat by name and would normally be put in the slush pile of non-actionable intelligence. The decrypt fingered by the US analyst used a German code word for Japan known to our agents in Tokyo, and by cribbing from that Johnson was able to isolate several dozen previous communications that we realized must have been going to the long-distance U-boats. Bingo, we had the code markers to look out for future messages. It was bloody clever, really. Pity he’s turned out to be a loose cannon.”
“Alan jokingly calls Bletchley ‘the machine,’ but he says it’s really an analog of the human mind, full of untapped potential but riven by human weaknesses.”
“Turing? Well, at least we can rely on him. He’s the other cryptographer in on this operation. He can take over Johnson’s work as well. He doesn’t seem to be affected by stress.”
“He runs it off. Hundreds of miles a week. We’re all affected by stress, whether we acknowledge it or not.” She closed the file. “So what do we do about convoy TS-37?”
Bermonsey tapped the cigarette again. “Officially, you and I came into this office to make the call to order that convoy to be rerouted, and as far as the rest of this hut is concerned, that’s what we’ve done. When they see tomorrow that the convoy has been hit, it won’t be the first time that’s happened. For every redirected convoy that makes it away in time, there are others that are just too sluggish. And there are U-boat captains who go maverick, changing course without sending signals that we might intercept. In normal circumstances, Werner Henke in U-515 is just that sort of captain. I know; I was one myself. In this instance, though, with his special assignment, we can be sure that he will stay on course. With the focus in the hut on the big convoy battle that everyone now expects in the North Atlantic, one that we have helped to set up today, the loss of a few ships off Sierra Leone will soon be history, even with their precious manganese ore. That’s the brutal truth of it.”