20 years ago, I worked with an ex-RE officer (who had been med discharged early as a result of a rubgy injury) and his father who was IIRC, a Lt.Col? in the RE at the time, had been a junior officer in the RE in the late 1960's and was on an exchange tour with a Kiwi army engineer unit that was then detached to Vietnam while he was on secondment. He went to Vietnam and did a combat tour with them.