sapper

noun3

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. — 1926
2. •
   (UK, informal) An officer or private of the Royal Engineers.
3. •
   a person generally engaged in digging requiring a level of professionalism

   • Let no Bank consider itself safe from the skill and daring of such sappers and miners. — 1847