Running out at right-angles from the frontline trenches were saps (narrow, shallow, trenches). This saps were about 30 yards long. Small groups of soldiers were sent to the sap-head (listening post) and were given the task of finding out about the enemy. This included discovering information about enemy patrols, wiring parties, or sniper positions. After a heavy bombardment soldiers would be ordered to seize any new craters in No Man's Land which could then be used as listening posts. From August 1916 all British Army units were under orders to occupy any shell-hole within 60 yards of their forward trench.