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A combat engineer, also called pioneer or sapper in many armies, is a soldier who performs a variety of construction and demolition tasks under combat conditions. 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. More generally, the combat engineer's goals involve facilitating movement and support of friendly forces while impeding that of the enemy.
Usually, a combat engineer is also trained as an infantryman, and combat engineering units often have a secondary role fighting as infantry. Beyond self-defense, combat engineers, infantry and assault troopers from armored corps units are generally the only troops that engage in the assault while dismounted. This role is limited by a lack of fire support (such as that obtained by infantry units from their mortars and recoilless rifles). However combat engineers typically do have extensive antiarmor capability in their infantry fighting role, such as with antitank missiles. There are no advanced academic qualifications required to be a combat engineer. The term "engineer" is not to be confused with the term applied to Professional Engineer or Chartered Engineer
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.
- In the American, British, Indian, Canadian, Australian, and New Zealand armies, is a term that is used for soldiers who have specialized combat engineer training.
- In the Israeli Defence Forces, Sapper 06 ( פלס 06 ) is a military profession code denoting a combat engineer who has graduated from basic general engineering training.
- In the Canadian Army the French language name for the Combat Engineer occupation is Sapeur de combat.
- In the Portuguese Army, a sapador de engenharia (engineering sapper) is a soldier of the engineering branch that has specialized combat engineer training. A sapador de infantaria (infantry sapper) is a soldier of the infantry branch that has a similar training and that usually serves in the combat suport sapper platoon of an infantry battalion.
- In the Finnish army, pioneeri is the private equivalent rank in the army for a soldier who has completed the basic combat engineering training. Naval engineers retain the rank matruusi but bear the pioneeri insignia on their sleeves.
- The german Bundeswehr uses the term "Pionier" for their combat engineers and other specialized units, who are associated with Special Forces to clear obstacles and perform engineering duties. Also the combat engineers in the Austro-Hungarien k.u.k. Forces were called "Pioniere".
- Assault pioneer:
- In the British, Canadian and Australian armies, an assault pioneer is an infantry soldier with some limited combat engineer training in clearing obstacles during assaults and light engineering duties. Until recently, assault pioneers were responsible for the operation of flamethrowers.
- Field engineer:
- is a term used (or formerly used) in many Commonwealth armies. In modern usage, it is often synonymous with "combat engineer". However, the term originally identified those military engineers who supported an army operating in the field as opposed to garrison engineers who built and supported permanent fix bases. In its original usage, "field engineering" would have been inclusive of but broader than "combat engineering."
Practices and techniques 
Combat engineers use practices and techniques of camouflage, reconnaissance, communication methods and enhancement of survival by other troops. Combat engineering also includes 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 carrying out demolitions, camouflage erection, field fortification construction, obstacle clearance, and obstacle construction, assault of fortifications, bridge erection, use of assault boats in water obstacle crossings, expedient road and 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.
All these role activities and technologies are divided into several areas of combat engineering:
Improving the ability of one's own force to move around the battlefield. Combat engineers typically support this role through reduction of enemy obstacles which include point and row minefields, anti-tank ditches, wire obstacles, concrete and metal anti-vehicle barriers, and Improvised Explosive Devices (IED) and wall and door breaching in urban terrain. Mechanized combat engineer units also have armored vehicles capable of laying short bridges for limited gap-crossing.
- Clearing terrain obstacles
- Overcoming trenches and ditches
- Opening routes for armored fighting vehicles
- Constructing roads and bridges
- Route Clearance
Building obstacles to prevent the enemy from moving around the battlefield. Destroying bridges, blocking roads, creating airstrips, digging trenches, etc. Can also include planting land mines and anti-handling devices when authorized and directed to do so.
When the defender must retreat it is often desirable to destroy anything that may be of use to the enemy, particularly bridges, as their destruction can slow the advance of the attackers. The retreating forces may also leave booby traps for enemy soldiers, even though these often wreak their havoc upon non-combatant civilians.
- Planting land mines
- Digging trenches and ditches
- Demolishing roads and bridges
- Explosive material handling
- Clearing fields of land mines
- Opening routes during assault
- Demolishing enemy structures (using bulldozers or explosive charges).
- Defense structures
Building structures which enable one's own soldiers to survive on the battlefield. Examples include trenches, bunkers, shelters, and armored vehicle fighting positions.
Defensive fortifications are designed to prevent intrusion into the inner works by infantry. For minor defensive locations these may only consist of simple walls and ditches. The design principle is to slow down the advance of attackers to where they can be destroyed by defenders from sheltered positions. Most large fortifications are not a single structure but rather a concentric series of fortifications of increasing strength.
Equipment and vehicles 
Combat engineers employ a wide range of transportation vehicles and equipment, and uses weapons unique to the engineers, including those used in land mine warfare.
Basic combat engineering tools include safe use of: driving tools and chopping tools (hammers, mauls, sledges, screwdriver, and bits); cutting tools and smoothing tools (saws, chisels, planes, files and rasps, brush-cutting tools, miscellaneous cutting tools); drilling tools, boring tools, and countersinking tools; measuring tools, leveling tools and layout tools (rules, tapes, marking tools, levels, plumb bobs, squares); gripping tools, prying tools and twisting tools (pliers, wrenches, bars); holding tools, raising tools and grinding tools (vises, clamps, jacks, grinders, and oilstones); timber handling tools and climbing tools; digging tools (shovels, posthole diggers, picks, and mattocks); portable power tools and trailer-mounted tools (electric tool trailer and generator, portable power tools); miscellaneous tools.
- Obstacle breaching
For obstacle breaching, including minefields, the combat engineers use a variety of vehicles, explosive devices and plastic explosives including:
- Minefield breaching devices
- Bomb disposal robots
- Explosives, mines and bombs
- Field-deployable bridges
Combat Engineering Corps 
Combat engineers are a key role in all armed forces of the world, and invariably found either closely integrated into the force structure, or even into the combat units of the national troops. In many countries, combat engineers are members of broader military engineering corps or branches. Examples of this include the Royal Australian Engineers, the Canadian Military Engineers, German military engineers the Irish Army Engineer Corps, the Corps of Engineers, Indian Army, the Corps of Royal New Zealand Engineers, the Pakistan Army Corps of Engineers, the Corps of Royal Engineers, and the United States Army Corps of Engineers. However, some nations have distinct combat engineering corps or branches which are separate from other types of military engineers. The Danish military engineering corps is almost entirely organized into one regiment of combat engineers, simply named Ingeniørregimentet ("The Engineering Regiment").
In the Israeli Defence Forces the combat engineers are organized under the Combat Engineering Corps (Hebrew: חיל ההנדסה הקרבית). In addition to Combat Engineering Corps (ICEC) sappers, each infantry brigade has an engineer company trained with basic engineering and EOD skills. ICEC sappers are often attached to other units (such as armored divisions or infantry) in order to help them breach obstacles and handle explosive threats. The ICEC operates advance engineering tools such as the IDF Caterpillar D9 armored bulldozer, IDF Puma armored CEV, Armoured vehicle-launched bridges, armored engineering vehicles, EOD robots and electromagnetic mine-detectors. Their main role is enabling Israeli forces to advance (breach the enemy's obstacles), stop the enemy's movement, handle explosives and perform construction and destruction missions under fire. The Israeli engineering corps is also responsible for counter-NBC warfare (i.e. defending troops against unconventional weapon and clean infected areas). The ICEC has a special unit, called Yahalom (in Hebrew it means "Diamond" but also abbreviation of "Engineering Unit for Special Operations") which handles EOD, commando, demolition and sabotage, engineering recon, advance robotics, tunnel warfare, maritime breaching, counter-NBC, and other classified tasks.
The Israeli Combat Engineering Corps (ICEC) was founded in 1947 and since then taken important part in all the wars of Israel. During the Yom Kippur War the ICEC breached the Suez canal, enabling IDF armor to invade Africa, destroy Egyptian SAM batteries and circle the Egyptian 3rd Army. In the northern front, ICEC IDF Caterpillar D9 bulldozer was the first motorized vehicle to reach the highest summit of Mount Hermon, preventing it from falling to Syrian hands. ICEC chief engineer, Brigadier General David Leskov, developed many combat engineering systems, and received three Israel Security Prizes, he served until his death at the age of 86. The ICEC took important part in many counter-terrorism operations. The IDF Caterpillar D9 armored bulldozers were key factor in keeping IDF casualties low during the Second Intifada, as they were impervious to Palestinian weapons and detonated safely thousands of IEDs and booby traps, some were big enough to destroy a main battle tank.
The Israeli combat engineer Corps motto is "Rishonim Tamid" Hebrew: ראשונים תמיד, meaning "Always first".
Historical Publications 
|FM 21-105 Basic Field Manual, Engineer Soldier's Handbook, 2 June 1943 ...|
|You are going to make sure that our own troops move ahead against all opposition, and you are going to see to it that enemy obstacles do not interfere with our advance. You are an engineer.|
- "Sapeur / Sapeuse de combat". Forces.Ca. Retrieved 2013-01-20.