An entrenching tool (UK), intrenching tool (US), E-tool, or trenching tool is a digging tool used by military forces for a variety of military purposes. Survivalists, campers, hikers, and other outdoors groups have found it to be indispensable in field use. Modern entrenching tools are usually collapsible and made using steel, aluminum, or other light metals.

Entrenching tools go back at least to the times of the Roman Legion who used a type of mattock known as a dolabra. Julius Caesar, as well as other ancient writers, documented the use of spades and other digging implements as important tools of war. The Roman Legion when on the march would dig a ditch and rampart fortified with mobile stakes around their camps every night where established camps were not available.

Siege tactics throughout history required the digging of fortifications and often mining of walls was attempted, where saps were dug to a wall's foundation, and collapsing the wall was attempted.

In more modern times the siege tactics of the Napoleonic Wars used spades and pickaxes as entrenching tools to dig trenches towards the walls of the fortifications being besieged, to allow men and munitions to get close enough to fire cannons at the walls to open a breach. Being too long and heavy to be transported by individual soldiers, entrenching shovels and spades were normally carried in the supply carts (logistics train) of a military column; only pioneer or engineer troops typically carried spades or shovels as part of their individual equipment. This frequently led to situations in which the infantry did not have access to entrenching equipment when it was needed. As one US army infantry officer noted, "the intrenching tools of an army rarely get up to the front until the exigency for their use has passed."

In 1870, the U.S. Army introduced the trowel bayonet, intended for individual soldiers as both a weapon and an entrenching tool. This was followed by the development of separate trowel and spade tools, small one-hand implements that could be carried as part of a soldier's individual equipment. While the entrenching trowel or spade gradually gave way in the United States and other modern armies to larger, heavier, and more effective entrenching tools, the concept of supplying each infantry soldier with a means of digging his own entrenchments or breastworks continued as a tactical doctrine.

The first truly modern entrenching tool was invented in 1869 by the Danish officer Johan Linnemann (infanteriofficer) [da]. In 1870, it was patented and supplied to the Danish Army. The next year it was adopted by the much bigger Austrian Army, and Linnemann founded a factory in Vienna to produce his spade. It was later introduced to Germany, France, Romania, and Russia, though only Russia recognized Linnemann's patent rights, and paid him 30,000 rubles and ordered 60,000 spades. The Russians called it the MPL-50 (small infantry spade that is 50 cm (20 in) in length) and still use it to this day. This little spade can also be used as an axe, a hammer, an oar, or as a frying pan for cooking food.

During World War I, entrenching tools became extremely important with the introduction of trench warfare. Entrenching tools designed for the individual infantryman soon appeared with short straight handles, T-handles, D-handles, and other designs.

The British entrenching tool of this period was a two part design, with a metal head and a wooden handle, the metal head consisted of an adze or spade blade and a pick axe spike, used alone the head could be used as a spade with the pick spike serving as a handle. Between the blade and the spike was a ring into which the handle could be inserted at right angles to the head, with the handle inserted the tool could be used as a pick mattock. Besides being used for digging defensive fighting positions, entrenching tools were used for digging latrines and graves.