A combat engineer (also called field engineer, pioneer or sapper in many armies) is a soldier who performs a variety of construction and demolition tasks under combat conditions.
The combat engineer's goals involve facilitating movement and support of friendly forces while impeding those of the enemy. Combat engineers build, repair and maintain buildings, roads and power supplies. They employ explosives for construction and demolition projects, and clear minefields using specialized vehicles. Such tasks typically include constructing and breaching trenches, tank traps and other fortifications, bunker construction, bridge and road construction or destruction, laying or clearing land mines, and other physical work in the battlefield. Typically, a combat engineer is also trained as an infantryman, and combat engineering units often have a secondary role fighting as infantry.
A general combat engineer is often called a pioneer or sapper, terms derived respectively from the French and British armies. In some armies, pioneer and sapper indicate specific military ranks and levels of combat engineers, who work under fire in all seasons, may be allocated to different corps, as they were in the former Soviet Army, or they may be organized in the same corps. Geomatics (surveying and cartography) is another area of military engineering but is often performed by the combat engineers of some nations and in other cases is a separate responsibility, as was formerly the case in the Australian Army. While the officers of a combat engineering unit may be professionally certified civil or mechanical engineers, the non-commissioned members are generally not.
Combat engineers are force multipliers and enhance the survival of other troops through the use and practice of camouflage, reconnaissance, communications and other services. These include the construction of roads, bridges, field fortifications, obstacles and the construction and running of water points . In these roles, combat engineers use a wide variety of hand and power tools. They are also responsible for construction rigging, the use of explosives, and the carrying out of demolitions, obstacle clearance, and obstacle construction, assault of fortifications, use of assault boats in water obstacle crossings, helipad construction, general construction, route reconnaissance and road reconnaissance, and erecting communication installations. Combat engineers build and run water distribution points, carrying out water filtration, and NBC decontamination when necessary, and storage prior to distribution.