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 man to a small number of soldiers.

The Tobruk name may have derived from its initial conception or idea by Rommel in the Siege of Tobruk and its defenses in Libya. Hence the name 'Tobruk'.

A foxhole is one type of defensive strategic position. It is a "small pit used for cover, usually for one or two men, and so constructed that the occupants can effectively fire from it."

It is known more commonly within United States Army slang as a "fighting position" or as a "ranger grave". It is known as a "fighting hole" in the United States Marine Corps, a "Gun-Pit" in Australian Army terminology, and a "fighting pit" in the New Zealand Army.

In British and Canadian military argot it equates to a range of terms including slit trench, or fire trench (a trench deep enough for a man to stand in), a sangar (sandbagged fire position above ground) or shell scrape (a shallow depression that affords protection in the prone position), or simply—but less accurately—as a "trench".

During the American Civil War the term "rifle pit" was recognized by both U.S. Army and Confederate Army forces.

During the fighting in North Africa (1942-43) Specifically in Tobruk - Libya, U.S. forces employed the shell scrape. 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 tanks, which could crush the man inside a shallow slit trench by driving into it, then making a simple half-turn.

...
Wikipedia