Ditch (fortification)

A ditch and earth bank at Old Sarum, near Salisbury in England, dating from the Iron Age.
Ditch of Valletta, which was built between 1566 and the 1570s.

In military engineering, a ditch is an obstacle designed to slow down or break up an attacking force, while a trench is intended to provide cover to the defenders. In military fortifications the side of a ditch farthest from the enemy and closest to the next line of defence is known as the scarp while the side of a ditch closest to the enemy is known as the counterscarp.