CHAPTER NINETEEN

RESTRICTED AREA

GENERAL GROVES HAD REASON to be suspicious. Goudsmit and his Alsos intelligence team had moved on from their thorium toothpaste adventure. General Groves had not. The Alsos investigation had left some critical questions unanswered: why was the town of Hechingen “a restricted area”? What were the Nazis hiding?

To find answers, RAF reconnaissance flights swept hundreds of square miles near Hechingen. The specially equipped Spitfires carried two cameras, one on each wing, which filmed overlapping images. Back in England, interpreters from Britain’s Air Scientific Unit studied the photos through stereoscopes which married the two images, producing what looked like a three-dimensional picture.

The interpreters spent countless hours looking for uranium processing plants and nuclear reactors. They had been briefed to search for a large industrial facility using enormous amounts of electricity. With so much territory to search, the interpreters used Germany’s electric power grid as a guide. They looked for large electric transformer stations and followed the high-voltage power lines radiating from them. It was painstaking, mind-numbing work, but it paid off.

The photo interpreters discovered more than a dozen medium-sized industrial plants under construction, stretching for twenty miles along a valley close to Hechingen. Each had a small factory building with storage tanks and what looked like a grid of pipes alongside. 180 The interpreters observed workers from nearby slave-labor camps building rail spurs and stringing power lines. They could see large quantities of material being brought in by truck and rail. Every reconnaissance mission brought new evidence of what was obviously an urgent, top-priority program. But it was a second piece of intelligence that bumped the program to the top of General Groves’ watch list: Werner Heisenberg had been spotted in the area.

As the interpreters grew more familiar with the imagery they noticed that the dozen or so plants were all strung along the same geologic contour. Armed with that additional bit of information, the Interpretation Unit sent an officer to Britain’s Geologic Museum. There, a curator searched through volumes of old records and discovered that German geologists had explored the area before the war looking for oil-bearing shale.

Germany was desperately short on gasoline. Allied intelligence concluded that the pipes alongside the plants were used to “cook the oil out of the shale.” What the reconnaissance had discovered was a crash program to refill Germany’s gas tanks. 181

Allied intelligence later learned that the German term “restricted area” which they interpreted to mean “top secret, keep out” didn’t mean that at all. It was simply a warning that the town, already flooded with displaced people from war-ravaged areas, was no longer open to refugees.