The Siege of Smerwick, during the Desmond rebellions, took place at Dún an Óir in 1580 leading to one of the major massacres of the Sixteenth Century in Ireland. James Fitzmaurice Fitzgerald landed a small Papal invasion force in July 1579, initating the second Desmond rebellion, but was killed only a month afterward. The landing did provoke a war that lasted for three years.
On September 10, 1580, 600 Papal troops commanded by Sebastiano di San Guisseppi (Italians and Spaniards), landed in Smerwick, near the same point where Fitzmaurice had landed the previous year. They had been paid for and sent by Pope Gregory to aid the rebellion. Desmond, Baltinglass and John of Desmond made an effort to link up with the expeditionary force but English forces under Ormonde and Grey blocked them and prompt naval action by Richard Bingham blockaded the Papal force’s ships into the bay at Smerwick. San Guisseppi had no choice but to fortify his men in the fort at Dun an Oir. In October 1580, Grey de Wilton with up to 4000 troops arrived at Smerwick and laid siege to the garrison. The invasion forces were geographically isolated on the tip of the narrow Dingle Peninsula, cut off by Mount Brandon, one of the highest mountains of Ireland, on one side, and the much larger English force on the other. They had no means of escape. In addition, the English had brought up heavy artillery by sea, which rapidly broke down the improvised defences of Dun an Oir.
After a three-day siege, commander Di san Giuseppe surrendered on 10 October 1580. Grey de Wilton, ordered the massacre of the invasion forces, sparing only the commanders. Italian and Spanish troops, and Irish men and women, were beheaded and their bodies thrown into the sea. According to folklore, the English spent two days decapitating their victims, lining them up one by one in a nearby field. Some of the corpses were used for target practice, but most were tossed into the ocean.
Today that field is known in the locality as Gort a Ghearradh (the Field of the Cutting) while the field where the heads were buried is bears the name Gort na gCeann (the Field of the Heads).