Talk:Operation Big

Sigma pile
Useful references here and here (German). BTW the device captured at Haigerloch was a sigma pile, i.e. a subcritical assembly for testing basic nuclear properties. Securiger 15:15, 27 Mar 2005 (UTC)

Anyone know enough to refine this assertion?

Definition here:


 * Sigma pile [′sig·mə ‚pīl]
 * (nucleonics)
 * An assembly of moderating material containing a neutron source, used to study the absorption cross sections and other neutron properties of the material.

Wikiuser100 (talk) 16:30, 11 June 2015 (UTC)

Boris T Pavel
I wonder if the Boris T Pavel quoted in this article is is the same person as Boris T Pash. KreyszigB (talk) 20:19, 30 March 2015 (UTC)
 * Yes I am sure that it should be Lt-Col Boris T. Pash, and will amend the article. Hugo999 (talk) 10:48, 31 March 2015 (UTC)

Alternative accounts
Alternative depictions of where facilities were, materiel seized, and personnel captured are found both at Atomic Heritage Foundation: The Alsos Mission and Beck, Alfred M, et al, United States Army in World War II: The Technical Services – The Corps of Engineers: The War Against Germany, 1985 Chapter 24, Into the Heart of Germany, p. 556-559

The large laboratory appeared to be in Hechingen, and another lab in Tailfingen where Otto Hahn and his staff were. The Beck account places the missing uranium ingots and heavy water in Tailfingen:


 * "The Allied technicians then moved to a plowed field outside the town to supervise a hastily impressed German excavation crew, whose digging uncovered a large wooden platform. Drawing back this cover, they found a neat stack of dark ingots – the missing uranium from the pile at Haigerloch. A nearby gristmill yielded up three large drums of heavy water, used to control the reaction in the pile."

The Atomic Heritage Foundation (which also refers to an Operation Harborage which appears to overlap or be another name for Operation Big) account places the large lab at Hechingen and the missing records in a cesspool at von Weizacker's home (wherever it was):


 * "The operation was initiated in April 1945 and Hechingen was captured on April 24th. Col. Pash seized a large atomic physics laboratory and took into custody several sought-after scientists including Otto Hahn, Carl von Weizacker, and Max von Laue. It was learned that Heisenberg, Gerlach, and a few others had left Hechingen two weeks prior and were possibly in Munich or at Urfeld in the Bavarian Alps. On the 27th, the German scientists were transferred to Heidelberg for further questioning, where information on the whereabouts of German atomic research records were revealed by von Weizacker. They were sealed in a metal drum which was stored in a cesspool in back of von Weizacker's house."

From Beck, et al:

Support of Alsos

In the last half of April, with German armies collapsing, Allied technical teams moved into Germany in the VI Corps area to capture German scientists, documents, and equipment in order to assess their contributions to the German war effort. Because of the progress the United States had made in achieving nuclear reactions in the Manhattan Project, the most urgent of these efforts sought intelligence on how close the German scientists were to building a fission bomb that, even at that late hour, might change the course of the war. An investigation team of nuclear scientists had already been active in Alsace, capturing almost 1,000 tons of uranium ore and various equipment in the 6th Army Group area. Associated with the American nuclear research effort in the United States and operating under the code name ALSOS, the team, commanded by Col. Boris T. Pash, now sought to seize the remaining uranium supply, Page 557 the research documents and laboratories, and the brains behind German nuclear science.44 To support these scientific teams, SHAEF assigned each army group command a so-called T-Force headquarters to which scientific personnel were assigned when they arrived in the theater. The technical experts and theoretical scientists usually were accompanied by a complement of combat troops to protect them and by combat engineers who could serve that purpose but whose main task was to dismantle captured equipment and laboratories. In General Devers’ headquarters, the I 269th Engineer Combat Battalion provided combat engineer support for the 6th Army Group T-Force. Intelligence gathered in ALSOS operations before the 6th Army Group crossed the Rhine pointed to the existence of a dispersed research complex centered on the villages of Hechingen, Bisingen, and Tailfingen nestled at the eastern edge of the Black Forest. Colonel Pash’s target area lay in a broad valley laced with the tributaries of the Neckar River, a region of charm and natural beauty. At the western end of the valley lay Freudenstadt, some twenty-five miles east of the Rhine at the same latitude as Strasbourg in Alsace. From Freudenstadt southeast curved a rough arc of small towns that marked the scientific mission’s line of advance across thirty-five miles of German countryside. Denied an airborne operation to secure this area, Pash decided instead on an unsupported thrust into the hills, risky as it was in the face of small and scattered, but still combat ready, groups of German soldiers and SS troops. Colonel Pash’s difficulties were compounded by the sudden successes of the First French Army. On 16 April the 6th Army Group had drawn army boundaries in the area to leave the city of Stuttgart in the Seventh Army zone of operations. French forces had cleared the east bank of the Rhine opposite Strasbourg by that date and General Jean de Lattre de Tassigny, ignoring General Devers’ restrictions on his movements, exploited his advantage to thrust north and seize Stuttgart by 22 April. This forced Colonel Pash to move his team across a French rear area, a feat that took resolution, considerable bluff, and occasional strong language with French soldiery. The French Provisional Government never knew the nature of the search missions, but suspected that General Devers hoped to capture the remnants of the Vichy French regime, which had taken refuge in the German city of Sigmaringen, some fifty miles south of Stuttgart. The 1269th Engineer Combat Battalion less its Company B, left behind with the 6th Army Group T-Force, joined the ALSOS team at Freudenstadt on the morning of 21 April; the engineer contingent became Task Force White, after its commander, Lt. Col. Willard White. The entire command of scientists, engineers, and British technicians was known as Task Force A.45 Page 558 The same morning Task Force A set out on Colonel Pash’s Operation BIG from Freudenstadt through the quiet town of Horb to Haigerloch, twenty miles east of Freudenstadt. Here the elated scientists made their first big discovery. As the engineer troops consolidated the group’s position in the town, the ALSOS team shot open a bolted door sealing the entrance to a cave in the side of a cliff. Inside, the team found a large chamber and several smaller rooms crammed with instruments, control boxes, and an array of cylinders described by a frightened German technician as a uranium machine. Though missing its uranium element, the device was an operating atomic pile, captured undamaged. While the scientists, with engineer help, spent two days dismantling the equipment, Colonel Pash led most of the engineers to the Bisingen-Hechingen area, the next populated complex. Spurred by statements of Germans captured at Haigerloch, the force went in search of the missing uranium and other German scientists in the vicinity. Early engineer patrols ran into increasing signs of enemy small unit activity. Bisingen itself was quiet when the engineer column snaked into the town, but as the scientists left to explore Hechingen four miles to the north, a skirmish between engineers remaining in Bisingen and some German stragglers set off a show of resistance to the American troops by the hostile inhabitants. Colonel White put the whole battalion on alert, and the incident passed without further development, though the men advancing into the last town occupied during Operation BIG were considerably more edgy for this experience. Early on 24 April, Company A, bayonets fixed, moved on Tailfingen, ten miles by road southeast of Bisingen. In Bisingen and Hechingen some twenty-five noted German nuclear physicists and their staffs had surrendered and under interrogation had revealed the location of other German technical facilities in the town Task Force A now approached. Although expecting resistance, the engineer column pulled into Tailfingen after encountering little more than a roadblock on the way. By noon the troops had established Task Force A in Tailfingen and had surveyed the area for signs of German military activity. The atmosphere here contrasted sharply with that in Bisingen the day before. The laboratory staff of nuclear physicist Dr. Otto Hahn was cooperative as was the burgermeister, and the task force soon had the information it needed. The last discoveries of Operation BIG were at hand. In a cesspool in the town the team found a large metal container holding the valuable secret research papers of the Hahn laboratory. The Allied technicians then moved to a plowed field outside the town to supervise a hastily impressed German excavation crew, whose digging uncovered a large wooden platform. Drawing back this cover, they found a neat stack of dark ingots – the missing uranium from the pile at Haigerloch. A nearby gristmill yielded up three large drums of heavy water, used to control the reaction in the pile. The engineers loaded this treasure aboard the battalion’s trucks with some strain, the scientists hardly concealing Page 559 their amusement at the surprise of the troops as they loaded the trucks. The deceptively light-looking stack of ingots, about two cubic feet in size, weighed over two tons, uranium being among the densest elements. With the entire supply of German uranium in Allied hands, Operation BIG ended, as did the 1269th Engineer Combat Battalion’s association with the ALSOS team. The battalion returned to the 6th Army Group T-Force at Munich in the closing days of the war.46 Engineer units were a central element in the last six weeks of the war against crumbling German forces in the heart of the Reich. In the war of pursuit that eventually cut Hitler’s dwindling territory in half, the race to the Elbe in the north and into Austria and Czechoslovakia in the south was a matter of bridges and open roads. Along lines of communications from French and Dutch ports to the most forward fighting front, engineers supported the advance that contributed to the final collapse of the Nazi regime.

Wikiuser100 (talk) 16:28, 10 June 2015 (UTC)