A sapper is an individual engineer soldier usually in British Army or Commonwealth military service.
Considered the most elite combat engineer soldiers in the United States Army, a Pionier in the German Army and a sapeur in the French Army, a sapper/combat engineer may perform any of a variety of combat engineering duties. Such tasks typically include bridge-building, laying or clearing minefields, demolitions, field defences as well as building, road and airfield construction and repair.
In other words, a modern sapper's tasks involve facilitating movement and logistics of allied forces and impeding that of enemies.