In order to break the deadlock at ANZAC, both sides began digging tunnels toward their enemy, often passing above or below each other's tunnels. Initially, tunnelling close to the surface was employed to extend front line trenches. This was safer than sapping, as the opposing side had no knowledge of the work until the surface was broken. Deeper tunnels rising to the surface in no man's land could be used as forward observation posts or, in the case of the attack at Lone Pine, used as positions from which to launch infantry assaults. Other tunnels remained underground to be used as listening posts or for offensive mines.
By the time of the August offensive, the ANZAC front line was honeycombed with tunnels and mine explosions had created many craters in no man's land. Prior to the infantry assault at Lone Pine, the Australians exploded three mines to create extra cover for advancing troops. Many of these troops advanced from an underground firing line that had been established 18 metres out from the original front line. Once the Turkish trenches had been captured, tunnels across no man's land were extended to create a safe passage for the movement of troops and supplies.
