Warfare Undergound discusses an aspect of ancient siege warfare most people aren’t aware of:
When thinking of siege warfare we imagine many things — the thunderous discharge of formidable artillery weapons, scenes of battering rams pounding city gates, or fearless warriors scrambling up ladders thrown against mighty ramparts. Shakespeare dramatises the full-blooded intensity of the battle for Harfleur in Henry V: ‘Once more unto the breach, dear friends, once more / Or close the wall up with our English dead’.However, ancient authorities such as the Greek historian Herodotus, describing the Persian siege of Barca in 510 BC, and the Roman general Julius Caesar on his capture of Avaricum in 52 BC, tell of a different kind of siege warfare, a type that was invisible and silent but no less dramatic. Men who were expert in underground siege methods laboured to outwit each other in subterranean passages known as mines and countermines.
The purpose of digging tunnels (‘galleries’) by miners was to collapse the walls of the besieged fortress, by burning (‘springing’) the timber props at the end of the gallery once the foundations were reached. This caused the walls to sink and split, allowing an assault to be made on the breach by main force, hopefully bringing the siege to a speedy conclusion.
In response to this fearful threat, the defenders had no choice but to send down counterminers to detect and break into the enemy’s mines, to see them off before any damage was done.
There were three ways a mine and countermine could become engaged. First, if the countermine was driven above an advancing mine, the counterminers could dig through to the mine below and pump in water to flood the enemy’s work. Second, if the countermine was driven below the mine, the counterminers could spring the end of their gallery, thereby collapsing the mine above. And third, the two galleries could break through head to head, leaving it to the courage of the opponents in hand-to-hand combat to decide the outcome.