I knew the term degauss from using CRT computer monitors, but didn’t know the origin of the term for eliminating magnetic fields. In World War II, Germany used magnetic mines that were triggered by ships’ hulls. I’ll quote Wikipedia so I don’t rephrase this incorrectly: “A large ferrous object passing through the Earth’s magnetic field will concentrate the field through it; the mine’s detector was designed to trigger at the mid-point of a steel-hulled ship passing overhead.” The term “gauss”, for Carl Friedrich Gauss, was used as the unit of measurement for the strength of the magnetic fields in the mines’ triggers, and thus “degauss” was used by the British for their countermeasure. Ships were degaussed by two methods, electromagnetic coils that could reverse the bias field being detected and a less expensive solution where an electrical cable was dragged alongside.