Behind the Lines

The Untold Story of the Secret Mission to Seize Nazi Map Data

The nature of.. combat in World War II gave geodesy new urgency. Hough’s orders were to follow the front, and ride the first tank into Berlin.

Note: The following is an excerpt of an article that appeared in the November 2019 issue of Smithsonian Magazine and is reprinted with permission.

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Entering German cities within days of their capture by Allied forces, a team led by U.S. Army Maj. Floyd W. Hough slipped into bomb-ravaged Cologne (above) in early March 1945. National Archives / U.S. Department of Defense

The fighting for Aachen was fierce. American planes and artillery pounded the Nazi defenses for days. Tanks then rolled into the narrow streets of the ancient city, the imperial seat of Charlemagne, which Hitler had ordered defended at all costs. Bloody building-to-building combat ensued until, finally, on October 21, 1944, Aachen became the first German city to fall into Allied hands.

USE Hough Passport Photo IMG 0034 Copy 2Rubble still clogged the streets when U.S. Army Maj. Floyd W. Hough and two of his men arrived in early November. “The city appears to be 98% destroyed,” Hough wrote in a memo to Washington. A short, serious man of 46 with receding red hair and wire-rimmed glasses, Hough had a degree in civil engineering from Cornell, and before the war he led surveying expeditions in the American West for the U.S. government and charted the rainforests of South America for oil companies. Now he was the leader of a military intelligence team wielding special blue passes, issued by Supreme Headquarters Allied Expeditionary Force, that allowed Hough and his team to move freely in the combat zone. Their mission was such a closely guarded secret that one member later recalled he was told not to open the envelope containing his orders until two hours after
his plane departed for Europe.

USE Military Occupation Handbook IMG 8626 Copy 2In Aachen, their target was a library.

HOUGHTEAM, as the unit was known, was made up of 19 carefully selected individuals. Four were highly educated civilians: an engineer, a geographer who had worked as a map curator at the University of Chicago, a linguist who spoke five languages, and the dapper son of a prominent Kentucky family who’d grown up mostly in Europe as the son of a brigadier general posted to various capitals as a military attaché. There were also ten enlisted men. One was a Japanese interpreter on loan from the Office of Strategic Services, the spy agency precursor to the CIA. Others had been through the secret Military Intelligence Training Center at Camp Ritchie, Maryland. Among the Ritchie Boys, as they were known, were European immigrants who had fled to the United States to escape Nazi persecution.

USE IF NEEDED Captured RfL Map With Nazi Insignia IMG 0090 Copy 2At Camp Ritchie they received training in interrogation and other psychological operations. Their job was to question European civilians about the movement of enemy troops, translate captured documents and interrogate prisoners of war. For the refugees among them, it was a chance to leverage their language skills and cultural familiarity to defeat the enemy that had uprooted their lives.

Along with 1,800 pounds of cameras and other equipment for creating microfilm records, HOUGHTEAM also carried 11,000 index cards detailing the holdings of the Army Map Service as well as numerous target lists of technical universities, government institutes, libraries and other places likely to have the materials they had been sent to capture. The lists also named German scientists who seemed likely to cooperate, and some who were not to be trusted.

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Captured German geodesists and their data laid the foundation for the first geodetic network covering the European continent. The National Archives

In Aachen, the library that Hough was looking for was at the Technische Hochschule, or technical university. Though it had been nearly wrecked by American bombs, thousands of books remained. But what caught Hough’s attention were the bundles of folders stacked outside. It appeared as if the Germans “had left a number of files all roped up ready to load onto trucks when they made a hasty exit,” Hough wrote. The abandoned documents included tables of exceptionally precise survey data covering German territory that the Allies had yet to reach—just what Hough was looking for. His team quickly microfilmed the material and sent it to the front, where Allied artillery units could immediately use it to improve their targeting.

The Aachen seizure was the first in a series of remarkable successes for HOUGHTEAM that promised not only to hasten the end of the war but also to shape the world order for decades to come. Little is publicly known about the true scope of the information that Hough and his team captured, or the ingenuity they displayed in securing it, because their mission was conducted in secret, and the technical material they seized circulated only among military intelligence experts and academics. But it was a vast scientific treasure—likely the largest cache of geographic data the United States ever obtained from an enemy power in wartime. Relying on Hough’s memos to his superiors in Washington and other declassified records about the mission, which are stored at the National Archives, in addition to private letters and other materials provided by the families of several team members, I have pieced together the outlines of this historic military feat. The operation seems all the more astonishing because it was executed by an unlikely band of academics, refugees, clerks and soldiers, all led by Hough, an Ivy League-trained engineer with a passion for geodesy, the centuries-old science of measuring the Earth with utmost mathematical precision.

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Captured German scientists created the Central European geodetic network at Hough’s request. Later the network expanded to cover all of Europe. The National Archives

In 20th-century warfare, men and machines could achieve only so much without exact location data to guide them. The Americans knew that the Germans had a trove of this material, and had most likely captured even more of it from the countries they had invaded, including the Soviet Union. If Hough and his team could exploit the chaos of war to hunt down this prize, they would not only help to finish off the Nazis but could give the Americans an incalculable advantage in any global conflict to come.

Hough’s orders, then, were to follow the front, and ride the first tank into Berlin.

These days, when the phone in your pocket pinpoints your location in seconds, it’s easy to forget just how new that technology is—the U.S. military launched its first GPS satellite only in 1978—and just how laborious it used to be to gather and synthesize definitive geographic data. Unlike a traditional survey used to determine property lines or mark the route for a new road, a geodetic survey of a region accounts for the curvature of the Earth and even variations in this curvature. That extra precision becomes more critical over long distances. The nature of combat in World War II gave geodesy new urgency, as it required coordinating air, ground and naval forces across far larger areas than ever before.

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Early in his career, Hough (at right) led survey parties across the American West, including a 1921 trip to Arizona. National Oceanic and Atmospheric Administration

Captured data could give the Americans a pivotal advantage in realizing what would become one of geodesy’s ultimate goals—creating a unified geodetic network that covered the entire globe. In such a system, any point on Earth’s surface could be defined by numerical coordinates, and its distance and direction from any other point calculated with precision. This capability would prove incredibly useful for any long-distance human endeavor, including guiding missiles to a target on another continent, as the Cold War would soon demand.

Not long after the fall of Aachen, the Allies’ military situation worsened. In December of 1944, the Germans mounted a counteroffensive, pushing through the Allied line in southern Belgium and Luxembourg in what became known as the Battle of the Bulge. Foul weather initially grounded the Allies’ superior air power, and the fighting dragged on into January.

Hough waited in Paris. The weather was miserable. Electricity was intermittent. The enlisted men relied on fireplaces for heat—when they could find coal or wood to burn. Everyone seemed to have a cold they couldn’t shake. HOUGHTEAM did what research they could in France and other friendly or neutral countries. They worked six days a week, mostly nibbling at the edges of the real mission, but made the most of their downtime.

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Hough’s team entered Saalfeld on April 17, 1945, just days after the U.S. 87th Infantry Division had captured the town and continued its eastward march. The U.S. Army

Raymond Johnson, a 24-year-old telephone company lineman from Chicago, explored the movies and cabarets of Paris and practiced a few words of French with local women, as he later wrote in an unpublished memoir his daughters shared with Smithsonian for this article. Berthold Friedl, a 46-year-old linguist who struggled to make small talk with the enlisted men when the group gathered in the evenings to drink wine, wrote a book in French about Soviet military strategy and philosophy of war that was published in 1945. “Dr. Friedl was not capable of idle chit-chat,” Johnson recalled.

Martin Shallenberger, 32, the Kentucky blue blood, spoke fluent German and French, and though he could be charming, the G.I.s found him arrogant, according to Johnson. They bristled when he made them wait while he paused to capture some scene with his Leica camera or the watercolor paint set he carried around.

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The Americans created a “black list” of untrustworthy German geodesists. The director of the Leipzig Observatory was “a Nazi of the worst type.” The National Archives

David Mills, a mild-mannered geodetic engineer, and Edward Espenshade, the geographer, were more at ease with the G.I.s. Espenshade collected rare books, especially pornographic ones, which he left out for all to inspect, including Mildred Smith, one of two Women’s Army Corps members on the team. A geography teacher from Illinois, Smith was brought on for clerical support, but Hough took note of her initiative and intelligence and assigned her to search the map shops of Paris, and later sent her on a research trip to London. The enlisted men called her Smitty. Some, like Johnson, had never met such a woman. “Up to this point in my life I had had little personal contact with the liberated type of woman who could read our underground books and discuss them with the men with perfect composure,” he wrote.

Hough remained busy. When the Belgians requested help microfilming some survey data and secret lists of artillery coordinates, he was happy to oblige—and saw to it that an extra copy was sent to Washington without the Belgians’ knowledge. When the French city of Strasbourg was recaptured by the Allies, his men removed a cache of top-quality German survey equipment before the French had a chance to claim the gear for themselves.

If an obstacle arose, Hough was willing to get creative. After several neutral countries balked at letting Espenshade and Shallenberger search their institutes and libraries, Hough procured letters from the Library of Congress certifying the men as its representatives engaged in bibliographic research. A similar ploy got Shallenberger into the pope’s private library at the Vatican, which was strictly off-limits to members of any military, owing to the Vatican’s status of neutrality.

Finally, by early March, the Allied forces resumed their eastward progress and were poised to cross the Rhine into the German heartland. HOUGHTEAM’s window of opportunity was opening.

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Hough’s team shipped 371 boxes of captured German equipment to the U.S., including this stereoplanigraph made by renowned German optics firm Zeiss. The National Archives

On March 4, Hough left Paris with Mills, his fellow engineer, and three enlisted men. They entered Cologne on March 7, and, the next day, toured the captured city’s massive Gothic cathedral, seemingly the only building to have escaped Allied bombing. On March 9, they received word that Bonn had been captured, and they made it there by nightfall. There they interrogated the director of the local geodetic institute, who led them to a hidden alcove that held a box of valuable books. The man claimed he’d stashed the materials there despite orders to evacuate them across the Rhine. “It is surprising that these Germans cooperate as they do,” Hough wrote in his daily memo to his superiors in Washington. Whether the scientist was anti-Nazi or was simply afraid of what the Americans might do to him, Hough wasn’t sure.

Hough and his men entered Frankfurt at the end of March, the day after it was captured, taking shelter in one of the few structures still standing in the business district. Buildings were still burning. Water was scarce. They found some in two bathtubs the Germans hadn’t drained before fleeing. But HOUGHTEAM’s target institutions in Frankfurt had been reduced to rubble. In the basement of one building, the men saw what looked like books, but they disintegrated into fine ash in their hands.

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In the German town of Saalfeld, Hough and his men captured the map and data repository of the German Army, which had been moved from Berlin to keep it safe from Allied bombs. The National Archives

In Wiesbaden, a city just to the west, their luck began to improve. In the basement of one building, they found 18 bundles of survey data, hidden behind a pile of rubbish. Marked “Secret” or “Confidential” in German, the sheets covered thousands of survey points in southwestern Germany. The data had immediate operational value for the U.S. Seventh Army, which was beginning to push its way across the Rhine into that area. Hough decided to shortcut the chain of command to get the information directly to the artillery units that could use it.

Hough and his team also got a tip from a captured officer of the Reichsamt für Landesaufnahme, or RfL, the German national survey agency; he revealed the names of two small towns, about 140 miles to the east in Thuringia, a hilly, forested region dotted with medieval villages, which had not been on any of Hough’s target lists.

USE Saalfeld Img019 Copy 2The U.S. Third Army was just moving into the area, which was famed for its artisanal bisque dolls, named for the unglazed porcelain that gave them a lifelike appearance. On April 10, Hough headed east with four enlisted men. In the small towns of Friedrichroda and Waltershausen, dispersed among three doll factories, private homes, a ranch house and a stable, the team found the entire archive of the RfL, which represented the German government’s best survey data of its own territory. The documents had been spirited from Berlin and hidden. It was by far the team’s biggest haul to date. “Cannot begin to estimate yet what is here but it is plenty,” Hough wrote.

On April 12, Hough and several of his men visited Ohrdruf, a subcamp of the infamous Buchenwald complex, and the first Nazi concentration camp liberated by American forces, just eight days earlier. Generals Dwight Eisenhower and George Patton visited Ohrdruf on the same day as Hough. “There are no words capable of expressing the horrible scenes on every hand,” Hough wrote. “It was revolting and we were left almost speechless.”

That night, Johnson and a few other HOUGHTEAM enlisted men stayed in a home in the nearby city of Gotha. In that stage of the war it was common practice for the Army to billet the troops in commandeered civilian homes. Johnson was struck by how familiar they felt. “They were charming and comfortable,” he recalled in his memoir. “Plants in the windows, closets full of clothes, children’s rooms with toys in them, sewing articles, cabinets full of good china and silver.” It seemed impossible to reconcile these cozy scenes of German domestic life with the horrors they had witnessed. One of the men sat vacantly burning holes in the upholstered arm of a chair. “There was nothing we could do that could measure up to the enormity of what we had seen,” Johnson wrote.

Days later Hough and his men interrogated several captured RfL officials, including the institute’s president, Wilhelm Vollmar, who tried the Americans’ patience and spent a night in jail as a result. Erwin Gigas, the chief geodesist, was more cooperative. A third German, whom Hough identifies only as “the real man we were interested in,” proved of more immediate value. They’d been searching for him since Wiesbaden…

Note: To read the rest of the story of how Hough and his men tracked down the central map and geodetic data repository for the German Army, including how the data was quickly put to use, please visit

Greg Miller is a science journalist and co-author of All Over the Map: A Cartographic Odyssey (National Geographic, 2018). A former neuroscientist, he has worked as a writer at Wired and Science, and lives in Portland, Oregon.