On 14 April 1945, the boat was quietly cruising at a depth of 200 feet only 8-10 miles off the British coast, when the commander, Kptlt. Schlitt, decided to use the toilet without consulting a rating trained in its operation (the procedure was complicated). Something went wrong, and when the specialist arrived he misunderstood the situation and opened the wrong valve, which resulted in large quantities of seawater entered the boat. The water reached the batteries directly under the toilet, causing the production of
chlorine gas, and the boat was forced to surface immediately; unfortunately right underneath an enemy aircraft. The crew managed to blow clean air into the boat, but were at the same time bombed by the aircraft, causing extensive damage which left
U-1206 unable to dive. Considering the hopeless situation, Schlitt had no choice but to destroy the secret material and order abandon ship to save his crew.