sapper

noun

1. A combat engineer; an engineer or a soldier engaged in attacking, destroying, and circumventing or building fortifications, bridges, and roads; a military engineer active in a combat zone.

   “his knowledge of Arabic and freedom from the theories of the ordinary sapper-school enabled him to teach the art of demolition to unlettered Beduin in a quick and ready way.”

   “A vast minefield trapped Ukrainian troops for weeks as infantry sappers slowly cleared an assault route on foot.”

2. (British, colloquial)An officer or private of the Royal Engineers.

   “By a remarkable piece of railway reconstruction work on the part of the Allied Forces—mainly South African railway construction troops—mines laid along the track by the retreating enemy were removed by sappers, and the German damage made good, within 7 days.”

   “Billinge, from St Austell, was one of the first soldiers to land on 'Gold' beach on June 6 1944. He was a sapper attached to the 44 Royal Engineer Commandos and was one of only four to survive from his unit.”