The First War of Physics (40 page)

In frustration, Pash returned to Washington in February with little to show for his efforts. Berg hadn’t budged far from Washington, still waiting for his travel orders.

Kesselring had advised the Allied forces that, because of the historical significance of the monastery on Monte Cassino, he had ordered his units not to occupy it. However, Allied reconnaissance reported German troops inside the monastery and it was believed that it would make too good an artillery observation post for the Germans not to use it. Clark’s infantry had mounted a series of attacks through January and early February, and had sustained heavy losses. Lieutenant General Bernard Freyberg, commander of the New Zealand Second Division of the Eighth Army, which replaced the bloodied American units, judged that men were more important than monasteries, and requested that it be bombed. The monastery was pounded to rubble on 15 February, but the bombing left the cellars intact, and German troops now moved quickly to occupy what remained and fortify their positions.

Further attacks were repelled, again with heavy casualties. The final assault was launched on 11 May 1944. Units of Moroccan troops versed in the art of mountain warfare penetrated a weak point in the German defensive line; though the point was weak only because the Moroccans were able to scale the ‘unscaleable’ Petrella Peak, which had been left undefended. On 18 May a Polish reconnaissance group found the monastery abandoned. On 25 May Kesselring’s fall-back defensive line was finally breached at Piedimonte San Germano. Two days earlier, the Allied forces trapped at Anzio had broken out and advanced from their beachhead.

Kesselring requested permission from Hitler to retreat from Rome, and Hitler agreed: Rome was a place of culture that had to be spared. Clark’s Fifth Army entered the city on 4 June. The occupation of Rome had been dearly bought. Over 54,000 Allied troops and 20,000 German troops had perished in the battle for Monte Cassino.

Berg’s travel orders finally came through and he departed from Washington on 4 May, heading for London. Towards the end of May he travelled to Algiers, and he was in Italy in early June. He checked into the Hotel Excelsior just two days after Rome had been liberated. Pash had got
there a little before him, following closely behind Clark’s jeep as it swept through the city early on the morning of 5 June.

Pash headed immediately for Amaldi’s home on Via Parioli. Amaldi was friendly and co-operative, and agreed to Pash’s request to remain in the city. He was no doubt surprised when, shortly after Pash’s departure, Berg turned up on his doorstep asking that he prepare to leave immediately for America.

When an agitated Amaldi appeared at Pash’s hotel to explain that he was now being asked to travel to Naples, on the orders of President Roosevelt, Pash smelled a rat. He had sat fuming through the winter months waiting on an OSS mission to spring Amaldi and Wick from Rome by submarine, a mission that not only never happened but, as he had discovered himself directly from Amaldi, never really existed at all. Amaldi explained that his visitor was waiting for him in the hotel lobby. Pash hastened to confront him, now full of rage at what he suspected was yet another example of OSS incompetence.

Berg remained slouched in an easy chair as Pash introduced himself.

‘Colonel, looks like you and I are going to have to reach an understanding’, Berg began.

Something in Pash snapped, as the Alsos and AZUSA missions collided. ‘Attention!’, he yelled. Berg scrambled to his feet, explaining that he needed to escort Amaldi to Naples because the Alsos mission was waiting for him.

Pash vented his frustration and hurled a torrent of abuse. ‘Captain,’ he said, ‘you are looking at the Alsos mission. No doubt you’re from OSS … You have no business in Rome. If I run across you again, I’ll bring charges, and I can think of plenty. Now get out …’

Rather nonplussed but undaunted, Berg returned to Amaldi’s home the next day. Pash did not understand the physics and had no choice but to wait for scientific members of the Alsos mission to catch up with him in Rome. But Berg understood enough of the physics and started his questioning immediately. He continued to talk to Amaldi, Wick and other Italian physicists as June wore on.

It turned out that the Italian physicists knew next to nothing about the German bomb programme. Although they had worked on nuclear fission before and during the early years of the war, they had not been approached by the German physicists or asked to get involved. Hahn had visited Rome in 1941 but had avoided discussion of nuclear fission research. Amaldi was sure that the Germans were working on fission but felt that nothing could come of this for ten years at least. He was convinced that Heisenberg was not working on a fission project, as Heisenberg was a theoretician, not an experimentalist.

Wick knew a little more about Heisenberg’s activities. Heisenberg had taught him physics in Leipzig and Wick had corresponded with his former teacher throughout the war. Heisenberg had written to him of the damage caused by the Allied bombing of Berlin and Leipzig. When asked where Heisenberg was now, Wick was cagey. He would say only that Heisenberg had moved south, to a ‘woody region’ of Germany.

Haigerloch

Gerlach realised that the Uranverein would make no progress with reactor research in heavily bombed Berlin. Earlier in the year, Bagge had overseen the evacuation of about a third of the Kaiser Wilhelm Institute for Physics to laboratory facilities established in Hechingen, the ancestral home of the House of Hohenzollern set against the backdrop of the Black Forest in south-western Germany. By the end of July 1944 many of the Uranverein physicists had relocated there. Hahn had moved with the Institute for Chemistry to Tailfingen, a village about ten miles south of Hechingen.

Heisenberg’s home in Leipzig had been destroyed by Allied bombing in December 1943. He had spent the first half of 1944 commuting between the laboratories in Berlin and Hechingen and the village of Urfeld, about 50 miles south of Munich in the Bavarian Alps, where he had moved his family to escape the worst of the bombing. He settled in Hechingen in the summer of 1944, leaving Wirtz in Berlin to oversee the reactor experiments.

Gerlach now scoured the neighbouring countryside for a new location suitable for reactor research, one in a narrow valley that could not be easily targeted by enemy planes. He found what he was looking for in Haigerloch, a picturesque medieval village about ten miles from Hechingen. The village is perched in a steep limestone valley formed by loops of the Eyach river, a tributary of the Neckar.

The Reich Research Council requisitioned an old wine cellar that had been hewn from solid rock at the foot of an imposing cliff next to the Swan Inn. It was in this cellar that equipment for the reactor experiments was installed. The Haigerloch laboratory was codenamed the ‘Speleological Research Institute’.

The biggest problem remained lack of sufficient quantities of heavy water. Although four drums of heavy water had been recovered from the sinking
Hydro
, these were heavily contaminated. More drums from the wrecked plant had followed, bringing the total amount of pure heavy water available to the Uranverein to about two and a half tons. Heisenberg had used more than half this precious supply for reactor experiments in a specially constructed bunker laboratory in Berlin. However, the reactor had been built from uranium plates, ‘for the sake of method’, despite the demonstrated superiority of lattice configurations using cubes of uranium. These experiments were largely unsuccessful and had taken the Uranverein no further forward.

More heavy water was needed for further experiments at both the Berlin laboratory and the reactor now being built at Haigerloch. However, the I.G. Farben works at Leuna were destroyed by Allied bombing on 28 July 1944, and with them went the prospects for a new heavy water plant. The heavy water concentration cells at the Vemork plant were dismantled in preparation for the journey to Germany in August. Half the cells would go to Berlin and the remainder would come to Haigerloch.

Some valuable assets, some liabilities

Just two days after the liberation of Rome, the Allies launched the largest combined amphibious and airborne assault in history against Hitler’s
Atlantic Wall. Operation Overlord was launched on 6 June 1944, with the objective of landing five divisions on the beaches of Normandy. It was a marvellously orchestrated attack. Elaborate deception played its part. Dummy planes and landing craft installed along the Kent coast – the only part of Britain that the Luftwaffe could now reconnoitre from the air – and German agents who had been ‘turned’ by MI5, all led Field Marshal Gerd von Rundstedt to expect an attack in the Pas de Calais. Had it not been for Field Marshal Erwin Rommel, sent by Hitler to take command of Army Group B in northern France in January 1944, the Normandy beaches would have been lightly defended.

But the defences that had been erected on Rommel’s orders had been probed secretly by British commandos aboard midget submarines. Tanks had been ingeniously adapted to drive through water and detonate land mines ahead of the invading forces. Even as the Allied forces embarked, German radar was tricked into thinking they would strike elsewhere along the coast. Bad weather also played a part. The forecast for 4 and 5 June had led Rommel to believe that an invasion was not imminent, and he had left for Germany for a weekend with his family. What German forecasters did not anticipate was that the weather would be fine again a day later.

The south shore of the Bay of the Seine had been divided into five targets: Utah, Omaha, Gold, Juno and Sword. Only at Omaha beach did the attack very nearly fail. Landed at low tide to avoid defensive obstacles, the troops of General Omar Bradley’s First Army found themselves exposed on Omaha’s steep rise, trapped in a ‘killing zone’ in the face of heavy defences manned by the veteran 352nd Infantry Division which, unknown to the Allies, Rommel had brought forward to defend the beach some months before. For a time the headlong collision of hot metal, flesh and blood evoked nightmarish scenes from the First World War. Elaborate timetables for achieving objectives sank into chaos and confusion. Establishing a foothold on Normandy soil had always been about throwing sufficient numbers of Allied troops onto its beaches, but it was the heroism of individuals that turned near-defeat into victory that day.

As the Allied forces took their first tentative steps into northern France, attention turned once again to the German atomic programme. The Alsos
mission to Italy had produced very little new intelligence, but was declared by all its senior sponsors as a success. A second mission was planned, following the front line troops into France. Pash was to continue as military leader, but this time there would be a scientific head of the mission, someone who knew the European physicists well and who could distinguish important scientific intelligence from irrelevancies or disinformation. After a brief search, Samuel Goudsmit was appointed, for reasons that he was unable to fathom. When a few months later he read the dossier on him that had been carelessly misfiled among his own papers, he learned that he had ‘some valuable assets, some liabilities’.

His assets clearly outweighed his liabilities, whatever they were. Goudsmit had studied physics at the Universities of Amsterdam and Leiden, and had carried out research with Friedrich Paschen in Tübingen in Germany and with Bohr in Copenhagen. Together with fellow Dutchman George Uhlenbeck he had in 1925 discovered the phenomenon of electron self-rotation, what later came to be called electron
spin
.
⁶
Both Goudsmit and Uhlenbeck had moved to the University of Michigan in 1927.

Goudsmit knew all the leading European physicists and their specialities, and spoke their languages, literally and figuratively. His aptitude for scientific puzzle-solving was well suited to the kind of detection that would be required for the Alsos mission. As a student in Amsterdam he had taken a course in police detective work.

He also had personal reasons for accepting a leading role in the second Alsos mission. His parents had been arrested in Nazi-occupied Holland in late 1942 or early 1943, and aside from a farewell letter from the Theresienstadt concentration camp he had heard nothing from them since. Goudsmit had appealed to Heisenberg for help, but as far as he knew nothing had come of it. He left for Britain in June 1944.

Pash insisted on some ground rules between Alsos II and the OSS in order to avoid a repeat of the embarrassing encounter in Rome. It was agreed that the OSS would continue its own atomic intelligence-gathering in neutral countries only. Goudsmit subsequently received copies of OSS reports on the German programme. These were largely circumstantial, attributing stories of explosions and fires to uranium research. The reports even included the rumour that a uranium bomb had exploded in Leipzig, killing several scientists.

On 25 August, the President of the provisional government of the French Republic, Charles de Gaulle, re-entered Paris in triumph. Pash was in among the French army units that entered Paris from the south, and was therefore among the first American army personnel in the newly-liberated city.
⁷
His target was the Collège de France, and Frédéric Joliot-Curie. Pash managed to dodge the sniper fire, found Joliot-Curie in his office and, very gently, took him prisoner. Together they celebrated the liberation of Paris with champagne, drunk from laboratory beakers. Goudsmit joined them on 28 August.

Despite the fact that Joliot-Curie had met a succession of Uranverein physicists passing through his laboratory, there was little he could add to the body of intelligence on the German atomic programme. He explained that he had received assurances from Schumann in 1940 that the Paris cyclotron would not be used for war research. In telling of his encounters, one name was new to the Alsos team: Kurt Diebner. If anyone was organising atomic weapons research in Germany, Joliot-Curie said, it would be him. Diebner’s name was placed close to the top of the Alsos watch list.

Further evidence of German atomic research remained stubbornly elusive until the liberation of Strasbourg towards the end of November 1944. Weizsäcker was known to have a nuclear physics laboratory in the city and an office at the university. But he was not among the physicists who had been found at the laboratory, pretending to be doctors (the laboratory was in a separate building on the grounds of Strasbourg hospital). For the first time in the mission, Goudsmit found himself interrogating enemy physicists. It was a grim business. ‘Thank God I didn’t know them personally,’ he wrote to his wife, ‘and I kept my own identity hidden until the very end, when I had them put on a truck and taken to a camp.’