Hitler’s Sunken Secret

Hitler’s Sunken Secret (2005) Deuterium, or “heavy hydrogen,” has a proton and a neutron in its nucleus where ordinary hydrogen has only a proton. Two atoms of it, bonded with one of oxygen, form a molecule of “heavy water.” Water that has been highly enriched in such molecules is itself known as “heavy water,” and is extremely effective at slowing down the fast-moving neutrons that drive nuclear chain reactions.

In the late 1930s, the Norsk Hydro power plant near Vermok was Europe’s leading source of heavy water. When World War II broke out, the plant became first a prize for the Germans (who seized it when they invaded Norway 1940) and then a target for the Allies (who spent the next four years trying to destroy it). Both sides were driven by the knowledge that access to heavy water could give Germany a functioning nuclear reactor, a supply of plutonium, and ultimately an atomic bomb.

In February 1944, with an Allied invasion of Europe imminent, the plant’s entire stock of refined heavy water was loaded onto the lake ferry Hydro for shipment, ultimately, to Berlin. Norwegian resistance fighters, acting on orders from London, sank the ferry with a delayed-action bomb, sending ship, cargo, and fourteen unlucky Norwegian passengers to the bottom of the lake. The Germans’ apparent indifference to the shipment—no military guards on the ferry before it sailed, no attempt to raise it after it sank—led to suspicions that the shipment had been a decoy, and that the real heavy water had reached Berlin by other means.
Only after D-Day did the truth become apparent: The German atomic bomb program was moribund by 1944. The heavy water shipment was destined for a low-priority research program designed to produce nuclear reactors for the postwar era. The Germans paid little attention to the ferry because they no longer saw heavy water as crucial to the war effort.
Hitler’s Sunken Secretis nominally about an expedition to find the sunken ferry and raise part of its cargo. It is also, to varying degrees, about the significance of heavy water, Germany’s wartime nuclear research, the sinking of the ferry, the vagaries of military intelligence in wartime, and the ethics of fighting a guerilla war in your own homeland. Footage of the expedition, shot both above and below the surface of the lake, dominates the file. It is a natural—perhaps inevitable—choice, but ultimately an unsatisfying one.

The story of the expedition is competently told, but has a perfunctory feel. After decades of sunken-ship documentaries it is difficult to find a fresh angle, and Hitler’s Sunken Secretdoes not even try. There are shots on the machinery-cluttered decks of the salvage vessel, shots of the explorers bending over sonar readouts, and shots of a crewman’s intent expression as he maneuvers a remotely-operated vehicle (ROV) toward the wreck. The Hydro is well-preserved in the deep, cold water, but she is a small, homely, utilitarian vessel (unlike Titanic or Bismarck) and the ROV does not linger over her remains.

The highlight of the underwater footage is the crew’s struggle to dislodge a steel barrel from the muddy bottom of the lake and winch it to the surface. Even that, however, ultimately feels like a routine piece of marine salvage. The one moment of genuine excitement in the expedition comes when the barrel is pried open and physicist Dave Wark uses a simple field test to determine that it does contain heavy water. Wark’s clear explanation of the test deftly puts viewers in the same position as the expedition members: knowing what result to look for, but not sure if it will appear. His excitement when the hoped-for reading does appear on his instruments is palpable, and contagious.

The film presents the expedition as a bid to resolve “one of the last great mysteries of World War II,” and subtly hints that the mystery involves Germany’s ability to build an atomic bomb. The packaging of the DVD is less subtle. Both its front and back covers carry the ominous question: “How close were the Nazis to having the atomic bomb?” This approach is, at best, misleading. The answer to that question (“not very”) has been well established since 1945, andnothing the expedition might conceivably recover from the wreck of the Hydro would change it. The expedition is actually after smaller historical game: Confirmation that the heavy water from the Norsk Hydro plant was actually loaded on the Hydro, not shipped out secretly with the ferry acting as a decoy.

Once tests on the raised barrel provide this confirmation, two other loose ends from the sinking fall into place. The barrels that floated to the surface of the lake as the Hydro sank were, as the now-corroborated shipping manifest records, buoyant because they were only partially filled with heavy water. It was those barrels (not some second, secret shipment) that turned up in Berlin at the end of the war.

Hitler’s Sunken Secretis, paradoxically, at its best when it moves away from telling the story of the expedition and becomes a straightforward historical documentary. It deftly recreates the sinking using a mix of eyewitness interviews, recreations, and scenes from a 1947 Norwegian film that “starred” the surviving resistance fighters. It carefully parses the difference between what the Allies knew at the time of the raid (that Germany might be close to completing a bomb) and what they knew after the invasion of Europe (that the bomb remained a distant dream). It succinctly explains the physics of nuclear chain reactions, and does it using an inspired style of animation that renders individual atoms as flexible water droplets rather than rigid clusters of tiny billiard balls.

All this could have been the basis of a fascinating story about secret weapons, secret agents, and the vagaries of wartime intelligence. Instead, it is background to a lackluster investigation of relatively minor historical questions.
A. Bowdoin Van Riper Southern Polytechnic State University bvanriper@bellsouth.net

Movie Posters