Defensive fighting position
A defensive fighting position (DFP) is a type of earthwork constructed in a military context, generally large enough to accommodate anything from one soldier to a fire team (or similar sized unit).
Tobruk protecting the entrance to the bunker that now houses the Channel Islands Military Museum. This turret from a Renault R35 was originally employed on a Tobruk at Saint Aubin's Fort, Jersey.
US Marines digging 'fighting holes' near the Iraqi border, 2003.
US Navy Seabees digging 'hasty scrapes', 2003.
US Navy Seabees near completed fighting position, 2003.
US Navy Seabees constructing a defensive machine gun position during training, 2010.
US Navy Seabees with a completed defensive machine gun position during training, 2008.
US Navy Seabees completed defensive machine gun position during training with camouflage netting and timber supports, 2010.
Modern militaries publish and distribute elaborate field manuals for the proper construction of DFPs in stages. Initially, a shallow "shell scrape" is dug, often called a ranger grave, which provides very limited protection. Each stage develops the fighting position, gradually increasing its effectiveness, while always maintaining functionality. In this way, a soldier can improve the position over time, while being able to stop at any time and use the position in a fight.
Typically, a DFP is a pit or trench dug deep enough to stand in, with only the head exposed, and a small step at the bottom, called a fire step, that allows the soldier to crouch on to avoid fire and tank treads. The fire step usually slopes down into a deeper narrow slit called a grenade sump at the bottom to allow for live grenades to be kicked in to minimize damage from grenade fragments.
When possible, DFPs are revetted with corrugated iron, star pickets and wire or local substitutes. Ideally, the revetting will also be dug in below ground level so as to minimise damage from fire and tank tracks. The revetting helps the DFP resist cave-in from near misses from artillery or mortars and tank tracks.
Time permitting, DFPs can be enlarged to allow a machine gun crew and ammunition to be protected, as well as additional overhead cover via timbers.
In training, DFPs are usually dug by hand or in some cases by mechanical trench diggers. On operations, explosives, especially shaped charges ("beehives"), may be used to increase the speed of development.
Developing and maintaining DFPs is a constant and ongoing task for soldiers deployed in combat areas. For this reason, in some armies, infantry soldiers are referred to as "gravel technicians", as they spend so much time digging.
Because of the large expenditure in effort and materials required to build a DFP, it is important to ensure that the DFP is correctly sited. In order to site the DFP, the officer in charge ("OIC") should view the ground from the same level that the intended user's weapons will be sighted from. Normally, the OIC will need to lie on his belly to obtain the required perspective. This ensures that the position will be able to cover the desired sector.