Gort na gCeann, meaning the field of the heads, sits roughly 500 metres south of the coastal promontory fort of Dún an Óir, and local tradition holds that the heads of several hundred people were buried there following one of the most brutal episodes of the Elizabethan wars in Ireland. The site at Gortnagan is classified as a sixteenth-century mass burial ground, and the place-names of the surrounding land preserve, in Irish, a precise if grim account of what is said to have happened there.

The events behind the burial ground date to November 1580. Earlier that year, a fleet of six ships carrying somewhere between 700 and 800 Spaniards, Italians, and Irish had sailed from Santander under the command of Sebastiano di San Giuseppe, arriving in Smerwick Harbour in September to support the Desmond Rebellion, a series of uprisings against English crown authority in Munster. The force occupied and began strengthening Dún an Óir, a small promontory fort on the western side of the harbour where a landowner named Piers Rice had built a small castle the previous year. The fortifications were still unfinished when the English government response arrived: Lord Grey commanded the land forces, joined by the Earl of Ormond, while Admiral Winter's fleet sealed off the harbour from the sea. The siege lasted just three days. Despite having provisions reportedly sufficient for six months and munitions enough for 4,000 men, the garrison of around 600 surrendered on 10 November. All but approximately twenty of them, including women, were killed that same day.

Local tradition, recorded by Cuppage in 1986, adds a further layer of detail to the aftermath. According to that tradition, the killing took place in a nearby field called Gort na Gearradh, meaning the field of the cutting, where the victims were decapitated. Their bodies were thrown into the sea, while their heads were buried separately in the area now associated with the Gortnagan site. Bodies that later washed ashore are said to have been given burial at Teampall Bin in the nearby townland of Caherquin. The place-names, still in use, map out the landscape of the massacre with a specificity that no monument marks and no official commemoration explains.