King John's Castle, Limerick, survives today as an impressive Anglo-Norman fortress in a commanding position along the eastern edge of the river Shannon. In the early months of 1642, when the Munster army of the Irish rebellion was admitted to Limerick, the Protestant and Anglo-Irish citizenry fled to the king's castle for protection, and were immediately besieged. To breach the masonry the besiegers used miners to make tunnels for the placing of timber props, ready for firing, underneath the foundations. The castle's defenders reacted by opening countermines to intercept the encroaching mines, hoping to save the walls from ruin. Substantial evidence for this 'military mining,' unusually, has survived to yield their secrets to today's archaeologists and military historians, providing a fascinating record of the exceptional events of the siege. Kenneth Wiggins brings together detailed documentary sources and unique archaeological discoveries in an expert assessment of the siege, embracing the drama central to the story while highlighting technology and strategies characteristic of 'underground' siege warfare'. KENNETH WIGGINS is an archaeologist based in Limerick; his master's thesis, undertaken at University College, Cork, was on the subject of military mining.