Sebastiano da Modena), paid for and sent by Pope Gregory XIII, and was a clandestine initiative by Philip II of Spain to aid the rebellion.

It was found later that none of the Spanish officers had a commission from King Philip, nor the Italians from Pope Gregory, though the latter had been granted indulgences for taking part.

Regarding the Papal force, the Irish historian Father CP Meehan commented: ".. in or about one thousand, ... most of them were brigands pardoned at the entreaty of Fitzmaurice on the strict understanding that they should clear out of the Pontifical States and take service under him in Ireland.

[5] On 5 November, an English naval force led by Admiral Sir William Winter arrived at Smerwick Bay, replenishing the supplies of Grey de Wilton, who was camped at Dingle, and landing eight artillery pieces.

The English forces began the artillery barrage on Dún an Óir on the morning of 8 November, which rapidly broke down the improvised defences of the fort.

In Grey de Wilton's account, contained in a despatch to Queen Elizabeth I of England dated 11 November 1580, he rejected an approach made by the besieged Spanish and Italian forces to agree to terms of a conditional surrender in which they would cede the fort and leave.

Grey de Wilton claimed that he insisted that they surrender without preconditions and put themselves at his mercy and that he subsequently rejected a request for a ceasefire.

Grey de Wilton's forces spared those of higher rank: "Those that I gave life unto, I have bestowed upon the captains and gentlemen that hath well deserved ...."[6] Sir Geoffrey Fenton wrote to London on 14 November about the prisoners that a further "20 or 30 Captains and Alphiaries [were] spared to report in Spain and Italy the poverty and infidelity of their Irish consociates.

[9]Cusack also mentions that some of the few who were spared summary execution actually suffered a worse fate: They were offered life if they would renounce their Catholic faith.

[8] In contrast, Grey's report mentioned: "Execution of the Englishman who served Dr Sanders, and two others, whose arms and legs were broken for torture."

[11][12] Richard Bingham, future commander of Connacht, was present and described events in a letter to Robert Dudley (Earl of Leicester), although he claimed the massacre was perpetrated by sailors.

Archaeologists have not yet discovered human remains at the site, although a nearby field is known as Gort na gCeann ('Field of the Heads') and local folklore recalls the massacre.