What People Don’t Know About the World War II Race for Nuclear Weapons

What People Don’t Know About the World War II Race for Nuclear Weapons

Larry Holzwarth - May 31, 2021

It is generally known the allied effort to produce the atomic bomb during World War II bore the name Project Manhattan District. One of the most highly classified programs in American military history at the time, The Manhattan Project consisted of several efforts in the United States, Canada, and Great Britain, under the overall command of Major General Leslie Groves. Scientists, engineers, technicians, researchers, and trades specialists contributed to the effort. They built factories and towns to support and house them. Teams conducted counter-espionage operations. And the military wanted to know how advanced the German effort to build an atomic bomb had become. Finding out became the responsibility of the Alsos mission.

What People Don’t Know About the World War II Race for Nuclear Weapons
Leslie Groves, head of the Manhattan Project and its contingent missions, in 1942. Wikimedia

A little-known fact of the Manhattan Project is its program conducted in Europe, known as the Alsos Project. Also under the command of General Groves, Alsos formed to determine how much the Germans knew, and how close they were to a working bomb. The primary goal of Alsos was not to deter the German effort, but rather to keep the technology they had developed from the Soviets, with an eye toward post-war Europe. From 1939 to 1943, numerous European scientists working in the Manhattan Project despaired of the Germans developing a bomb first. In 1943 General George Marshall suggested the development of a special project, to be put in place in Italy under Allied occupation, later expanded into France and Germany. Here is the story of that program, known as Project Alsos.

What People Don’t Know About the World War II Race for Nuclear Weapons
Chief of Staff George Marshall (in uniform) with Secretary of War Henry Stimson. Wikimedia

1. The Americans assumed the Germans were ahead in developing an atomic bomb

Several of the scientists working in the Manhattan Project fled from Europe as Hitler consolidated power in the late 1930s. They came from other European countries besides Germany, among them Enrico Fermi, Leo Szilard, and Emilio Segre. The Europeans were of a mind that the Germans were ahead of the American effort, and expressed their concerns to General Groves. Groves informed George Marshall. Until the Allies invaded Italy, the Americans could do little to determine German progress, beyond intelligence obtained through spies and informants. Allied strategy assumed the Germans were developing an atomic bomb, and that the whole industrial complex of German-occupied Europe supported the effort. In 1943, with Allied troops occupying parts of Italy, General Marshall directed an effort be launched to ascertain as much as possible regarding the German program.

Marshall created the Alsos project via a memo in late 1943. “It is very likely that much valuable information can be obtained…by interviewing prominent Italian scientists in Italy”, he wrote. Marshall directed Groves to create a “small group of civilian scientists assisted by the necessary military personnel” to conduct the interviews. Marshall directed General Groves to personally select the civilian personnel, with the assistance of Dr. Vannevar Bush, and the support of military intelligence (G2). Groves selected Lt. Col. Boris T. Pash to command the Alsos Project. One of Groves’ first actions regarding Alsos was to protest over its name. Alsos, in Greek, means groves. The general expressed concern the name would draw attention to his role in the project. In the end, he decided to let it stand, believing changing it would draw even more.

What People Don’t Know About the World War II Race for Nuclear Weapons
A poster designed to remind workers in the vast Manhattan Project of the necessity for strict security. Wikimedia

2. The Alsos Project placed the Manhattan Project at risk of exposure

Those qualified to perform the duties of the Alsos Project, as envisioned by Marshall, had by necessity needed to know the breadth and scope of the American effort. Because of the nature of the security clearances issued for the Manhattan Project, most had specific knowledge of certain areas, and only general knowledge of others. Their access to information outside of their specific work in the project was limited by the concept of the need to know. As scientists, they had limited experience in extracting information via interrogation. They also posed the risk of inadvertently revealing classified information related to the Manhattan Project. Groves selected those individuals he believed offered the most promising abilities as potential interrogators. Translators also joined the team, as interviews in several languages were required.

At the end of 1943 American and British military planners expressed confidence that Rome would soon fall into Allied hands. An overseas headquarters for Alsos opened in London. Alsos established liaison offices in areas already occupied by Allied troops. Of immediate concern among the senior American officers and scientists was the likelihood the withdrawing Germans would force those with knowledge of the weapons program to withdraw with them. In December, 1943, the first phase of the Alsos mission assembled in Algiers, in preparation to travel to Italy. This mission included American major league baseball player Morris “Moe” Berg, later famous as The Catcher Was A Spy. The mission succeeded in contacting Italian scientists Gian Carlo Wick and Edoardo Almadi. Neither of the Italians admitted to having any involvement with the German atomic weapons programs.

What People Don’t Know About the World War II Race for Nuclear Weapons
Alsos team members analyzing acquired documents in 1944. Wikimedia

3. By the end of 1943 German atomic weapons capability was doubted by the Allied commands

The information delivered by the first Alsos mission provided little hard knowledge regarding the German research into atomic weapons. None of the Italian scientists interviewed had direct knowledge of the German effort. Nor did they believe the Germans capable of producing an atomic weapon within a decade. They based their surmises on information from the scientific community available before the war, rather than direct knowledge of current research. In other words, the first Alsos mission could neither confirm nor deny the existence of a German atomic weapons program. Allied leaders had no more or less information regarding the German effort than before the mission. They did extract some information in other technologies of use to the war effort, in particular regarding other advanced German weapons.

The mission remained in Italy in the spring of 1944, supported by armored cars and reconnaissance vehicles operated by the Royal Air Force. They planned to enter Rome immediately after the German defenders withdrew from the city. While waiting for that delayed eventuality, they interviewed senior Italian military and government personnel. The Germans continued to hold Rome. By late March, most of the Alsos team withdrew to the United States or London in frustration. Rome did not fall to the Allies until the first week of June, 1944, only two days before D-Day in Europe. When it did, Colonel Pash and a second Alsos mission flew to the city, joined days later by another team from the United States. Scholastic and government agency files were confiscated, at least two Italian researchers taken into custody, and several interviewed. Some members reported the Germans were not close to acquiring an atomic weapon.

What People Don’t Know About the World War II Race for Nuclear Weapons
Colonel Boris Pash commanded the Alsos missions in Europe throughout their existence. US Army

4. The Alsos mission in London conflicted with the team in Italy

As the Alsos team in Italy analyzed information and interviewed scientists and engineers they came to the belief the Germans were many years away from developing an atomic bomb. At the same time, the London team came to the conclusion the Germans were near having, and possibly had already, atomic weapons, possibly in the form of radioactive weapons. They arrived at the conclusion through interrogation of the hundreds of refugee European scientists and engineers exiled in Great Britain. They also compiled German scientific literature and documentation, papers, and private correspondence. Britain’s Norwegian desk at MI6 analysis of the German effort indicated radioactive weapons were in the German stockpiles. Analysis of aerial photographs provided by the RAF and USAAF led to the conclusion of German possession of significant amounts of uranium and thorium. They concluded these supplies were located near weapons manufacturing centers in occupied Europe.

Groves found himself with significantly conflicting reports. Those from Italy downplayed the German capabilities, while those from his analysts in London provided a grimmer picture. For Groves, the possibility of the Germans resisting the upcoming invasion with radioactive weapons foretold a looming disaster. Groves dispatched one of his staff, Army Major Arthur Peterson, to present their findings to General Walter B. Smith, Chief of Staff to General Eisenhower. He also informed Ike of the findings personally. Smith received his briefing in early April 1944, only two months before D-Day. After some debate, the planners decided to implement steps to counter a German attack with radioactive devices and informed the British of the need to adopt similar countermeasures. Preparation for encountering radioactive devices quickly became the purview of the hastily planned and executed Operation Peppermint.

What People Don’t Know About the World War II Race for Nuclear Weapons
Eisenhower received warnings from Alsos the Germans could defend the Normandy beaches with radioactive weapons. US Army

5. Operation Peppermint assumed the Germans had operating nuclear reactors and radioactive weapons

For the Germans to attack using radioactive devices, they first needed the means of producing them. The devices envisioned by Alsos mission reports required operational nuclear reactors. Alsos assumed the Germans had such reactors at several suspected locations. Operation Peppermint fell under the aegis of the American Assistant Chief of Staff for Operations (G-3), Major General Harold Bull. Bull immediately made the decision, endorsed by Groves, not to inform any of the operational commanders involved in the invasion of Normandy. Operation Peppermint remained highly classified at the senior staff level and officially came under the overall Manhattan Project. It was almost entirely a logistics effort. It required obtaining necessary radiation detection equipment and training operators in their use, held ready for deployment should the need arise. Medical personnel received training in treatments for radiation poisoning.

Operation Peppermint added one more burden to the heavy load borne on Eisenhower’s shoulders as the days ticked down towards the invasion of Europe. Similar reports regarding chemical and gas attacks preceded the invasions of Sicily and Italy in 1943. Those had led to the Allies prepositioning gas weapons of their own, which in turn led to a catastrophic mustard gas incident in the harbor of Bari. An American cargo vessel sank following a German aerial attack, releasing toxic liquid mustard into the harbor. Hundreds of casualties among Allied seamen and troops resulted from exposure to the toxins. A similar nightmare presented itself to Ike as June approached. Operation Peppermint planned to detect radioactivity and possibly limit the exposure to Allied troops, but no effective military countermeasure existed. In the end, one wasn’t necessary. The Germans did not have radioactive weapons.

What People Don’t Know About the World War II Race for Nuclear Weapons
Linking a radioactive bomb with V-weapons presented serious concerns for the British in 1944. Wikimedia

6. Alsos was enlarged for deployment in France

On April 4, 1944, US Secretary of War Henry L. Stimson created a new, considerably larger Alsos mission for deployment to France. Colonel Pash assumed command of the new mission, which reported through G 2 and G 3 to General Groves. Following the invasion in June, American, British, Canadian, and Free French forces remained bottled up in Normandy for several weeks. The Alsos mission spent its time analyzing the same data as had its predecessor. It also worked with British and French agents to identify key scientists in occupied France with likely knowledge of the German atomic weapons program. At this point, several key British officers and scientists lobbied their government to create a separate British program. In part, the British expressed concern over the American-led program’s failure to produce any hard, accurate information regarding the German pursuit of atomic weapons.

The British concern came from the very real peril their homeland came under from the German V-weapons. Great Britain had borne the burden of German aerial attacks for nearly five years. A German radioactive device delivered by a V-2 rocket on a British city presented a terrifying situation. The British considered developing their own missions for several weeks before agreeing to continue to work within the Alsos missions, under the command of Colonel Pash. When a breakout finally occurred in Normandy, supported by a second invasion in the South of France, Alsos teams moved to the continent. Their first mission in France included the location of scientists with experience in the necessary fields to build nuclear reactors and created atomic weapons. Near the top of their list appeared the eminent French physicist, Frederic Joliot-Curie.

What People Don’t Know About the World War II Race for Nuclear Weapons
Postage stamp portrait of French scientist Frederic Joliot-Curie, a highly desired source of information by the Alsos mission. Wikimedia

7. The search for Frederic Joliot-Curie

In early August 1944, OSS operatives in Washington informed Colonel Pash in London that the French physicist Joliot-Curie had been located in Brittany. With Brittany not yet under Allied control, Colonel Pash and a CIC Special Agent traveled to France and moved with Patton’s Third Army until the Americans secured L’Arcouest. Joliot-Curie owned a vacation home in the seaside area. When Pash and the agent, Gerry Beatson, arrived they found the home empty. They obtained nothing of the Frenchman’s papers, nor the physicist himself. The former had been removed by the Germans, and no information regarding Joliot-Curie could be found. A search of the records at the nearby University of Rennes provided some documentation regarding his work, but no clues to his whereabouts. The Alsos Mission team joined its operational support group, known as T-Force, at Rambouillet, preparing to enter Paris in late August.

T-Force joined in the liberation of Paris on August 24, 1944, and raced to Joliot-Curie’s suburban home. He was not there, but the Alsos team learned he could be found in his laboratory at the College de France in Porte-d’Orleans. The area at the time had not been fully secured from the Germans, and upon arrival, T-Force joined in the fighting being led by the Free French 2d Armored Division. The Alsos mission advanced to the college under fire from the Germans, which they returned with their small arms. When they arrived, they found Joliot-Curie in his laboratory and conveyed him to safety before the Germans could seize him. The Frenchman underwent brief interrogation in Paris before being flown to London for further conversations with Alsos senior scientists. He provided a great deal of information regarding the extent of the German atomic weapon programs.

What People Don’t Know About the World War II Race for Nuclear Weapons
As crowds cheered French troops entering Paris fighting continued in parts of the city and its suburbs. Wikimedia

8. The Alsos mission underwent grave risk in Paris to obtain a great reward.

The second Allied jeep to enter Paris during the liberation of that city carried Colonel Pash and three other operatives determined to secure Frederic Joliot-Curie at all costs. The French physicist was so knowledgeable regarding nuclear physics he had been mentioned by Albert Einstein in his pre-war letter regarding an atomic bomb sent to Franklin Roosevelt. Pash and the Alsos teams reasoned, correctly as it turned out, German scientists involved in a weapons program would consult with the Frenchman. Simply identifying the scientists involved offered a coup to the Alsos mission. If those scientists could be captured or otherwise induced to surrender to the Allies their services would be denied to the Soviets, then swept through Poland into Germany.

Several of the scientists identified by Joliot-Curie as having visited him became of immediate interest to the Allies. Some worked in high levels of the German atomic weapons program. Others worked in areas of additional interest, including Erich Schumann. Schumann worked throughout the war in biological warfare, including the use of pathogens to attack the American homeland. Hitler approved research into biological weapons as a means of developing suitable defensive measures against them. Schumann supported their use as an offensive weapon. Schumann came under Allied control (British) following the war, another German scientist denied to the Soviets. Several of the scientists identified by Joliot-Curie were interned in Britain at Farm Hall. There they thought they enjoyed relative freedom, though their activities were under audio and visual surveillance at all times, their conversations recorded for later analysis.

What People Don’t Know About the World War II Race for Nuclear Weapons
UMHK mines in the Belgian Congo made the company the world’s largest producer of uranium in the 1930s. Wikimedia

9. The Alsos mission established headquarters in Paris in 1944

As summer turned to fall in 1944, and the Allied armies advanced across France toward the Rhine, the Alsos mission established headquarters in Paris. An extensive search began in the then Allied-occupied areas, for scientists, evidence and records of their work, and physical components of the German weapons programs. In early September the Alsos mission sent a six-man team to join the British forces set to enter the Belgian city of Brussels. Prior to the war, Belgium had been the largest supplier of uranium ore in the world. The Belgian UMHK corporation held a virtual pre-war monopoly on uranium mining and distribution. Its headquarters in Antwerp, and its uranium refining facility in Olen, both offered critical sources of information for the Alsos mission. Incidentally, most of the uranium used by the Manhattan Project came from UMHK, shipped from the Belgian Congo directly to the United States.

The six-man Alsos team traveled to Brussels, where British Lt. Col. David Strangeways provided them with an attachment of armored cars to accompany them to Antwerp. The city had been captured by British troops, but the estuary remained in German hands and the region far from secured. In Antwerp, the Alsos team learned of over 1,000 tons of refined uranium shipped to Germany. Learning of approximately 150 tons at Olen, they arrived there to discover about 80 tons had been shipped to Toulouse prior to the German invasion in 1940. 68 tons of uranium at Olen were shipped to the United States under the direction of General Groves. The Alsos team went to Toulouse to attempt to locate the uranium there. They found only 31 tons, stored in barrels in a French arsenal. It too, was shipped to the United States. The remaining 49 tons have never been found.

What People Don’t Know About the World War II Race for Nuclear Weapons
A German soldier looks out over Strasbourg before its capture by the Americans in 1944. Wikimedia

10. Strasbourg became of interest to the Alsos teams in November, 1944

While the Alsos teams tracked uranium from Belgium across Europe, (more had been located in Eindhoven), others evaluated and analyzed information provided by captured scientists, logs, and research facilities. From information obtained at Rennes, Eindhoven, and other sites across Western Europe, Alsos analysts learned of extensive German scientific activities in Strasbourg. The University of Strasbourg served as a working facility for two well-known German physicists, Carl Friedrich von Weizsacker and Rudolf Fleischmann. Both had been pre-war nuclear physicists of international fame (at least among the scientific community). Strasbourg also housed a Junkers manufacturing plant where work on jet propulsion continued in 1944. The combination of jet aircraft and atomic weapons appeared plausible to the Alsos team.

There also appeared to be evidence of work at the University of Strasbourg supported the German biological weapons program, information gleaned from documents obtained at Eindhoven. An Alsos team traveled to Saarburg after communicating with the US Sixth Army as it prepared to enter Strasbourg. On November 25, Alsos teams entered the German nuclear laboratory and captured Rudolf Fleischmann. Von Weizsacker fled before Sixth Army entered the city. They discovered records indicating the conduct of biological agent experiments in German concentration camps. Materials recovered at Strasbourg revealed the Germans had failed to develop the process for uranium enrichment required for an atomic bomb, a list of sites where experiments and research were conducted, and the personnel involved. Alsos could then state with conviction the Germans did not possess an atomic bomb, nor were they close to building one.

What People Don’t Know About the World War II Race for Nuclear Weapons
The surprise German offensive known as the Battle of the Bulge increased the fear they were close to deploying atomic weapons. US Army

11. Despite the evidence, rumors swirled the Germans had an atomic bomb

In late 1944, as his Thousand Year Reich crumbled around him, Hitler’s propaganda machine exhorted the German people to fight on, promising total victory. Speeches were peppered with references to fighters and bombers, massive new tanks all being turned out by German industry, according to the propagandists. The rockets and jet bombers were soon to be equipped with new bombs, larger and more powerful than the world had ever seen. Meanwhile, the Germans began trying to hide the evidence of their most criminal activities, and the Allies ground inexorably toward Germany itself. In December 1944, the German Army launched its final offensive on the Western Front, a thrust through Belgium to capture the port of Antwerp and split the Allies. The Germans called it Unternehmen Nordwind. To the Allies, it became known as the Battle of the Bulge.

The Germans gained some initial successes in the offensive, to the great embarrassment of the Allied intelligence community. Almost unanimously, intelligence sources assured the Allied Supreme Command the Germans were no longer capable of such an offensive. The intelligence failure prior to the Battle of the Bulge brought all intelligence gathering and analysis operations under a cloud of suspected incompetence. Though the Alsos mission knew the Germans had not completed an atomic bomb and were in fact several years away from doing so, that information remained classified. German hubris, the propaganda machine, the emergence of jet fighters over the battlefronts, and plain old gossip kept the rumors of a German super bomb alive. Alsos missions during the Battle of the Bulge stalled. It seemed to many as if the war would go on indefinitely.

What People Don’t Know About the World War II Race for Nuclear Weapons
V-2 attacks on Belgium, including Antwerp, added to the speculation the Germans possessed radioactive weapons (dirty bombs) late in the war. Wikimedia

12. The Alsos mission identified scientists who needed to be kept from the Soviets

As the fighting increased in the Ardennes during the winter of 1944, Alsos missions withdrew from Strasbourg, destroying many of their own records in the process. A long-standing myth of World War II is that the majority of the V-2 rockets launched during 1944 were directed at Great Britain in a return of the Blitz. More V-2s targeted Belgium in late 1944 than any other European country. Late in the year, a massive explosion occurred when a V-2 fell short of its target in Antwerp. The size of the explosion and general nervousness over the German atomic weapons program led to demands Alsos investigate the site of the blast. Alsos, by then aware the Germans did not possess atomic weapons, nonetheless complied, sending an operative to confirm there had been no nuclear event.

During the lull in activity, the Alsos teams analyzed the rafts of data accumulated to that point, and prepared lists of German scientists and engineers. They prioritized the lists based on interviews already accomplished. Their new goal, to capture as many as possible before they fled deeper into Germany, necessitated a change of tactics. Alsos teams prepared to go behind the front lines, ahead of the assault troops, to prevent their quarry from escaping to the Soviets, or their capture by German partisans. When it became apparent that several of the highest priority targets were believed to be in areas designated to be occupied by French troops, Alsos planners decided to get to them first, ahead of their French allies. Examination of papers captured in Strasbourg revealed the whereabouts of several of the most senior personnel involved. Alsos planners created additional armed teams to seek them out.

What People Don’t Know About the World War II Race for Nuclear Weapons
After Oranienburg was assigned to the Soviet zone of occupation, Groves requested the research facilities there be bombed by the Army Air Force. US Army

13. The Alsos mission moved into Germany in early 1945

By March, 1945, Alsos teams returned to Strasbourg, and opened another facility in Aachen. From there analysis of captured documents revealed extensive atomic research in several locations, some still out of reach of the Allied Armies. When Alsos missions identified an industrial facility at Oranienburg as a thorium and uranium processing site, General Groves prevailed on the 8th Air Force to bomb the facility. Plans called for the Soviets to occupy the site post-war. The still persistent rumors of the German’s possessing atomic weapons ensured ready cooperation from the Army Air Force, and Alsos used the fear to their advantage. Over 600 bombers pounded the Oranienburg site; the bombing forced several of the most senior German scientists involved in the processing of uranium to flee eastward. There they fell into the path of the Soviets, who had created an Alsos team of their own.

The Americans were soon aware of the presence of Russian atomic scientists in NKVD uniforms in Oranienburg and other targeted regions. The Soviets too captured several German scientists, including Nikolaus Riehl and Gunter Wurths, who directed the uranium processing efforts at Oranienburg. When the Soviets requested a meeting with the German scientists in Berlin shortly after capturing the city, the Germans complied. They found themselves transported to the Soviet Union shortly thereafter. As Riehl awaited transport from Berlin, Soviet operatives dismantled his temporary laboratory and sent it to the Soviet atomic weapons program site in the Soviet Union. The Soviets recovered almost 100 tons of processed uranium oxide from the Oranienburg site, an indication their own atomic weapons program had advanced further than previously suspected.

What People Don’t Know About the World War II Race for Nuclear Weapons
In the closing days of the war in Europe, post-war politics affected battlefield operations on all fronts. Wikimedia

14. The Alsos mission had to thwart its French allies to capture some of the most important German scientists

As the Allies penetrated deeper into Germany, Alsos teams advanced with them, capturing some scientists and engineers, as well as documents which led them to others. By then Germany had been sliced into occupation zones by the diplomats of the Big Four Allied nations – the United States, Britain, Soviet Union and France. Papers captured by Alsos teams in several German cities revealed several of the most pre-eminent scientists on their target lists, and a wealth of uranium and experiment results, resided in the Wurttemberg area of Germany. The region lay in the direct path of the advancing French army, which was to occupy it after the war. Groves asked Marshall in Washington to reassign the region to American troops. Marshall could not persuade the State Department to agree, unless he explained why. Concerned as ever with secrecy, Groves refused. Instead, he and Marshall turned to Eisenhower.

Groves wanted Ike to approve an American assault in the region, after which the Americans would cede the ground to the French. Alsos teams would extract what they could and destroy the rest, leaving little if anything to the French. Plans for an airborne operation, capturing an airbase for the use of the Alsos team, were scheduled for late April. Two days before the plan was to be executed the French captured an intact bridge over the Neckar River, allowing them access to the entire area in strength. With a wealth of atomic research information and several important German scientists directly in the path of the French army, Groves and American combat commanders decided on a series of ground-based hit and run raids behind the German lines. Just as Alsos had attempted to deny access to the Soviets at Oranienburg, it would do the same to French near Wurttemberg.

What People Don’t Know About the World War II Race for Nuclear Weapons
An Alsos team and support technicians dismantling a German uranium research reactor near Haigerloch in 1945. US Army

15. Alsos missions engaged German troops as they sought atomic weapons facilities

The Alsos teams advanced ahead of the French Army, behind German lines, supported by a detachment of combat engineers. The missions occurred between April 23 and May 3, 1945. They encountered German resistance, engaging the enemy in firefights as Alsos scientists investigated several atomic research sites. They discovered an intact experimental nuclear reactor which they immediately took apart and shipped back to the American lines. At Hechingen, they captured more than two dozen German scientists, including the long-sought Weizsacker. Tailfingen yielded Otto Hahn, considered by many to be the prize of prizes, as well as several other important researchers. On May 1 they captured Werner Heisenberg, another physicist who had long remained elusive. A German combat group of about 700 men surrendered to the Alsos team on May 3.

As the Alsos team withdrew, Colonel Pash returned with a battalion of American troops, who took the 700 Germans into custody as prisoners of war. The Alsos team retained the captured scientists, and all the Americans withdrew to their own established zones. The French occupied the area May 4, 1945, for the most part, unaware of the activity. What they did know Eisenhower explained to de Gaulle as an overextension during a combat pursuit. Eisenhower also made the decision to treat the captured German physicists and scientists as prisoners of war, but in separate facilities from combat troops and other German civilian prisoners. They were sent to Kransberg Castle, in the German state of Hesse, while plans were made on how to best exploit them and their knowledge. How to use the prisoners became the object of Operation Epsilon.

What People Don’t Know About the World War II Race for Nuclear Weapons
Farm Hall, where British and American agents secretly recorded the conversations between captive German scientists. Wikimedia

16. The Germans were dismayed to find themselves prisoners of war

All of the German scientists captured by the Alsos missions considered themselves civilians, which in fact most were. They believed themselves exempt from incarceration as prisoners of war. They also had long enjoyed special privileges in Nazi Germany, due to their preeminence in their respective fields. As prisoners, at first, they received what they regarded as harsh treatments. The Allies had but recently learned of the extent of Nazi atrocities in Europe. Across the continent, intensive searches for escaping Nazis and collaborators continued. Those in captivity were treated with disgust by their guards. Amenities were few, they remained under near constant observation by guards. Many were held in isolation, released only for interrogation by their Allied captors. Some expressed fear for their lives. Had they known the value the United States and Great Britain placed on their knowledge they would have likely been less fearful.

In June, 1945, after recommendation from General Groves, Eisenhower concurred with a plan to transfer 10 prominent scientists then in custody at Kransberg Castle to England. There they were to be held in relative comfort at a quiet estate. They were to be given the freedom of the grounds, mail privileges, access to personal comforts and food, and even alcohol on some occasions. The site selected to house them, an estate named Farm Hall, not far from Cambridge, underwent renovations to receive them. The renovations included the installation of audio listening and recording devices and preparation of staff, all of whom spoke fluent German. They were provided with radios and record players, and the Alsos team developed plans for first-run movies and other forms of entertainment and recreation for their prisoners. Alsos wanted to make the Germans as comfortable as possible as they recorded their private conversations.

What People Don’t Know About the World War II Race for Nuclear Weapons
The Germans collectively expressed disbelief of the American’s success developing the atomic bomb. National Archives

17. Farm Hall revealed very little additional information on German atomic bomb research

The Germans found themselves comfortably ensconced at Farm Hall. They enjoyed considerable freedom around the house and grounds, unaware of their being continuously monitored and recorded. The recordings were on gold plated disks, which were analyzed, with transcripts prepared of conversations deemed useful. Others, mostly of a private or personal nature, were not transcribed and the disks erased. The disks were then reused. In one conversation, between Kurt Diebner and Karl Heisenberg, the subject of surreptitious listening devices arose. “I wonder whether there are microphones installed here”, said Diebner, who had administered the German atomic bomb effort. Heisenberg laughed it off, replying the British and Americans were not, “…as cute as all that”. The British kept the recording for their own amusement.

In August 1945, the Americans used the world’s first atomic bomb over Hiroshima, followed a few days later with another, of a different design, over Nagasaki. The Germans at Farm Hall learned of the news, most of them displaying disbelief. None of the German scientists could accept the fact the Americans had been so far ahead of them in nuclear research. Otto Hahn expressed his relief that his program had failed to deliver such a weapon to Hitler in time to use it in the war. Others expressed shame at their failure, while they could not comprehend the success of the Americans, attributing it to defected Germans and in some cases to Jewish refugee physicists in the United States and Great Britain. The internment of the German physicists and chemists at Farm Hall ended on January 3, 1946, having produced about 250 pages of transcripts of information.

What People Don’t Know About the World War II Race for Nuclear Weapons
Japan’s Unit 731 and research into other WMDs led to an Alsos mission to the Pacific in 1945. Wikimedia

18. The United States implemented an Alsos mission for Japan in 1945

During the war, American intelligence agencies and the scientific community harbored little concern of the Japanese developing an atomic bomb. Japan simply lacked access to uranium needed for both research and the eventual construction of such a weapon. However, the Americans grew concerned over the Japanese use of another weapon of mass destruction, biological weapons. Alsos revealed the extent of biological weapons research by the Germans, which included documentation exchanged with the Japanese. By 1945 the Germans had an extensive inventory of biological weapons, though Hitler refused to authorize their use. The Fuhrer had himself been gassed on the Western Front during the First World War. Historians have since speculated that may have led to his refusal to deploy gas and biological weapons during the Second World War. At any rate, they had them, but did not use them against Allied troops.

The Alsos mission for Japan operated independently of those for Europe, and was originally envisioned as being part of the invasion forces planned for Japan. Deployed to Manila in the summer of 1945, the mission, entirely American in make-up, prepared to examine the Japanese biological, chemical, and nuclear programs in a manner similar to the Alsos teams in Europe. Armed support groups similar to Europe’s T-Force trained to operate with the Alsos teams. After the Japanese surrendered in September, 1945, the teams deployed to Japan and China to examine the records and interrogate the personnel of the Japanese weapons of mass destruction programs. General Groves concerned himself only with the Japanese nuclear research programs. He learned, through Alsos missions, the Japanese had assigned low priority to an atomic weapon. Lacking uranium there was little else they could do.

Also Read: Deadly Smoke: The Worst Chemical Weapons Attacks of the 20th Century.

What People Don’t Know About the World War II Race for Nuclear Weapons
An Alsos team in France, late 1944. US Army

19. The German atomic weapon program proved much smaller than expected

When the senior scientists for the Alsos missions reviewed the scale of the German research into atomic weapons they expressed dismissal. Samuel Goudsmit, the senior scientist for the Alsos mission, personally inspected some of the German research sites, including those unearthed in Haigerloch. He wrote to General Groves of the site, describing it as “…compared to what we were doing in the United States…small-time stuff”. Later Goudsmit speculated over the usefulness of the Alsos missions, which placed numerous scientists, engineers, and support troops at considerable personal risk. “Sometimes we wondered”, he wrote, “if our government had not spent more money on our intelligence than the Germans had spent on their whole project”. The Alsos missions knew, as did Generals Groves, Marshall, and Eisenhower, the Germans were years away from an atomic bomb by 1944. However, that fact remained classified for years after the war.

Despite the heavy security surrounding the American atomic bomb, Soviet espionage agents and spy rings penetrated both the Manhattan Project and the German efforts during the war. Although the Alsos missions deprived the Soviets of several of the most notable German scientists involved, and much of their records, the Soviets acquired many others. Many of the records obtained in Alsos raids had already been copied and sent to the Soviet Union by its many agents in Germany during the war. The Soviet atomic bomb program did not really gain momentum until 1942, when the Manhattan Project’s programs were well underway. In 1949, the Soviet Union successfully detonated an atomic bomb, aided in a large part by the materials stolen from the Manhattan Project in the United States and the German efforts during World War II.

What People Don’t Know About the World War II Race for Nuclear Weapons
General Leslie Groves addressing a group of service personell at Oak Ridge, Tennessee, during the Manhattan Project. US Army

20. The Alsos missions did little to alter the course of the Second World War

If the Alsos missions revealed anything, it was the fact the Germans were years away from developing a working atomic bomb. Werner Karl Heisenberg later stated that he and many of his colleagues deliberately impeded the effort to build such a weapon out of moral considerations. Heisenberg’s recorded conversations at Farm Hall did not reveal such reticence. Instead, they blamed Germany’s failure to produce a weapon on the low priority granted to the program. Though some have claimed the German atomic weapons program became Hitler’s highest priority, in fact, it received little attention following 1940 since it evidently could not produce a weapon for many years to come. It received limited resources and financial support. It lacked a unified command structure. Political and personal rivalries dominated among its contributors. Alsos revealed these failings. For years those findings remained classified.

General Groves, who led the Manhattan Project for the United States, argued the Germans failed to build an atomic bomb because they never developed the industrial base needed to produce one. Lack of raw materials also contributed to the failure, as more and more dwindling supplies went to the conventional warfare needs. America’s Manhattan Project consumed about $2 billion to produce the bombs which fell on Hiroshima and Nagasaki, about $29 billion today. Germany’s atomic weapons program consumed roughly $2 million measured in 1945 dollars, less than the cost of a single U-boat. The Alsos missions did little to alter the course of the war because the Germans were never close to possessing the bomb. Alsos missions proved it beyond doubt.


Where do we find this stuff? Here are our sources:

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