Defensive fighting position A defensive fighting position ( DFP ) is a type of earthwork constructed in a military context , generally large enough to accommodate at least one person . Terminology . It is known more commonly within United States Army slang as a " fighting position " , or the slang term " ranger grave " , within United States Marine Corps slang as a " fighting hole " , in Australian and New Zealand Army Corps ( ANZAC ) forces terminology as a " fighting pit " , in Australian Army terminology as a " Gun - Pit " , within the British and Canadian military argot as a " slit trench " , or simply — but less accurately — as a " trench " . A foxhole is one type of defensive position . History . Early in World War II , during the fighting in North Africa , U . S . forces employed the " slit trench " . This was a very shallow excavation allowing one man to lie horizontally while shielding his body from nearby shell bursts and small arms fire . The slit trench soon proved inadequate in this role , as the few inches of dirt above the soldier ' s body could often be penetrated by bullets or shell fragments . It also exposed the user to assault by enemy tank s , which could crush the man inside a shallow slit trench by driving into it , then making a simple half - turn . After the Battle of Kasserine Pass , U . S . troops increasingly adopted the modern " foxhole " , a vertical , bottle - shaped hole that allowed a soldier to stand and fight with head and shoulders exposed . The foxhole widened near the bottom to allow a soldier to crouch down while under intense artillery fire or tank attack . Foxholes could be enlarged to two - man fighting positions , as well as excavated with firing steps for crew - served weapons or sump s for water drainage or grenade disposal . Tobruk . The Germans used hardened fortifications in North Africa and later in other fortifications such as the Atlantic Wall that were in essence foxholes made from concrete . The Germans knew them officially as " Ringstände " ; the Allies called them " Tobruks " because the Allies had first encountered the structures during the fighting in Africa . Frequently , the Germans put a turret from an obsolete French or German tank on the foxhole . This gave the Tobruk enhanced firepower and the gunner protection from shrapnel and small arms . Modern defensive fighting positions . Modern militaries publish and distribute elaborate field manuals for the proper construction of DFPs in stages . Initially a shallow " shell scrape " is dug , much like a very shallow 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 dug deep enough to stand in , with only the head exposed , and a small step at the bottom that allows the soldier to sit down in the hole to avoid fire and tank treads . Also , there are usually deeper , narrow slits called grenade sump s at the bottom to allow a grenade to be kicked in to minimize damage . 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 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 DFT , it is important to ensure the DFT is correctly sited . In order to site the DFT , the officer in charge 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 .