Hans Kammler was a German civil engineer and SS-Obergruppenführer who became one of Nazi Germany's most powerful construction and armaments managers. Born in Stettin in 1901, he earned a doctorate in engineering, joined the Nazi Party in 1931 and the SS in 1933. From 1941 he led SS construction within what became the SS Main Economic and Administrative Office, where his Office C designed and built the concentration and extermination camps. On 26 September 1941 he ordered construction of the largest camp at Auschwitz, and historian Nikolaus Wachsmann writes that he was involved in all the major building projects there, including the crematoria planned at Birkenau in 1942.

After British bombers struck Peenemünde in 1943, Kammler oversaw moving V-2 rocket production into tunnels in Thuringia, the Mittelwerk, built and worked by concentration camp prisoners held in what became the Mittelbau-Dora camp. Historian Michael Neufeld estimates that about 10,000 prisoners lost their lives producing the V-2, roughly twice the number the weapon killed in Britain and Belgium, and more than 20,000 perished at the camp in all. In 1944 Kammler took control of V-2 operations from Walter Dornberger and gained authority over jet aircraft construction, and in early 1945 Hitler named him head of all missile projects. Two former SS men stated at their 1958 trial that he had ordered the killing of some 200 forced laborers and family members in the Arnsberg Forest in March 1945.

His fate in 1945 is disputed. He disappeared in the last days of the war, and a 2019 Wilson Center working paper by Frank Döbert and Rainer Karlsch cited American records indicating that U.S. forces held and questioned him in May 1945, without settling what became of him afterward. That gap made Kammler a fixture of postwar speculation about German technology passing to the United States, alongside the documented transfer of rocket engineers such as Wernher von Braun.

The best-known claim is Die Glocke, or the Bell. Polish author Igor Witkowski described it in his 2000 book Prawda o Wunderwaffe as a bell-shaped SS device said to have been tested in Lower Silesia, and British journalist Nick Cook brought it to English readers in The Hunt for Zero Point (2001), proposing that Kammler traded such technology to the U.S. military for his freedom. Historians and critics have found no wartime record of the device. Writer Jason Colavito called it "a hoax, or at least a wild exaggeration," and skeptic Brian Dunning noted that its absence from the historical record makes its existence increasingly unlikely.

Kammler returned to the headlines in September 2026, when Liberation Times published Christopher Sharp's report "The Kammler Connection." Unnamed intelligence-community sources quoted in it alleged that Kammler was a link between Nazi efforts to exploit recovered technology, including a claimed 1933 Italian recovery near Magenta, and a postwar American UFO legacy program. Sharp's article called that larger story unverified and noted that a key page placing Kammler in American custody had no identified archival original. The engineer whose documented record rests on camps, slave labor and rockets has thus become, eight decades later, a central name in claims about hidden programs.