Career
He is known for his theory that the mythical city of Atlantis was located in Tunisia. Borchardt argued that the Shott el Jerid swamp, generally thought to mark the site of Lake Tritonis, was in fact the original Atlantic Sea referred to by Plato. Borchardt also identified Mount Atlas as being a peak in the Ahaggar Mountains, rather than in the Atlas range.
He believed he had discovered Atlantean ruins at Qabes, but these ruins were later found to be of Roman origin.
During World World War II, Borchardt was incarcerated at Dachau, due to his Jewish ancestry. He escaped to Britain in 1939, and thence to the United States.
He was arrested and put on trial for spying in 1941, and was sentenced to 20 years imprisonment. His early release was secured in 1952 due to petitioning from the German government, but he died less than a year afterwards.