CHAPTER FIFTEEN

HEAVY WATER IV

AFTER THE DARING COMMANDO attack, British intelligence estimated it would take the Germans twelve months to repair the Norsk Hydro plant. But it was up and running again in just six, prompting the Allies to plan a third attack. 131 This time it was an American operation.

As the Eighth Air Force squadron of B-17’s approached the Norwegian coast, it was 22 minutes early. The workers at the plant had not yet taken their lunch break. They were not in the basement cafeteria, safe from the Allied bombs soon to be headed their way. To kill time the squadron commander turned back towards the North Sea executing a wide 360-degree turn.

By the time they returned, the Germans were ready. One bomber was shot down by ground fire; another was hit and the crew forced to parachute into the sea. 132 One hundred and seventy-six planes made it inland to Vemork and the Norsk Hydro plant where they were joined by 29 B-24 bombers. Together they dropped more than 700 bombs. None of them scored a direct hit. The company’s power plant was damaged, but the “high concentration” plant where the heavy water was produced went untouched. The local residents paid the steepest price: 21 Norwegian civilians killed. 133

Once again, the Germans were quick to make repairs. In February 1944, just seven weeks after that third attack, a shortwave operator with the Norwegian resistance sent an urgent message to England’s Special Operations Executive. SOE ran Britain’s sabotage operations in Europe. The Norsk Hydro plant was back in business and preparing to send the Germans a 15-ton shipment of heavy water. Thirty-nine barrels of the precious liquid would be loaded into two freight cars and transported by rail to a nearby port where the cars would be transferred to a rail-ferry for the next leg of the journey across Lake Tinnsjø. 134

The Norwegian heavy water shipments were the weakest link in Heisenberg’s atomic supply chain. The Germans knew it, and the Allies knew it. With such a large shipment at risk, the Germans took extraordinary precautions. The plant already had armed guards, anti-aircraft guns, land mines and machine guns. The Germans added still more troops and sealed off every possible entry except the main gate. They brought in a special army detachment backed by a regiment of SS police to guard the railroad tracks and ride the freight cars transporting the heavy water to the port. A squadron of spotter aircraft was positioned at a nearby airfield to assist with aerial reconnaissance. 135 Several troops were assigned to the port to guard the ferry.

The Norwegian resistance fighters had no good options. The plant itself was too well guarded, as was the train. The best option was to sink the ferry. Plant managers, who were working with the resistance, scheduled the crossing for a Sunday morning when they anticipated there would be the fewest passengers. Some of them and some crewmembers would likely die in the icy waters. It was a terrible price to pay. And the Germans might make it a lot worse.

In the past, the Gestapo had executed civilians in retaliation for killing German soldiers. In one instance, they had destroyed an entire town: “Every house and building burned down, every boat in the harbor sunk, every animal killed, and the entire community . . . sent to various concentration camps.” 136

A resistance shortwave operator wired London: “Doubt whether the effect of the operation is worth the reprisals. As we cannot decide how important the operation is, we request a reply soonest.”

Within hours London wired back: “The matter has been considered and it’s decided it is very important to destroy STOP Hope it can be done without great misfortune.” 137

The stage was set for a fourth attack on the Norwegian heavy water. On a frigid Sunday morning, the Hydro, a rail ferry with 53 passengers and crew, started its journey across Lake Tinnsjø. Below deck, hidden in the bilge near the bow, were nineteen pounds of plastic explosives attached to an alarm clock. Resistance saboteurs had set the timer to go off 45 minutes after the scheduled departure, when the ferry would be over the deepest part of the lake. 138

The alarm went off as planned. The explosives ripped through the hull. Twenty-six passengers and crew perished in the freezing waters. 139