This instance gives a very good indication of the relaxed and honourable nature of close relationships in sixteenth century Gaelic Ireland. However, when much stricter English inheritance rules were introduced into the lordship of Tyrone in 1542, with the creation of the earldom of Tyrone, the introduction of primogentiture (succession from father to eldest son), created a huge amount of fear and resentment of Ferdoragh O'Neill from Conn Bacach's other sons, particularly the formidable Shane O'Neill. Shane O'Neill was only a young child when Ferdoragh O'Neill was recognised as eldest son and heir by their father Conn Bacach O'Neill, but when he grew to adulthood Shane seized on the issue of Ferdoragh's origins and began to claim that his elder brother was not an O'Neill at all but a Kelly.
The Blacksmith Kellys from Dundalk may have been quite wealthy and they appear to have owned a castle or tower house on Dundalk's main street. The mid nineteenth century editor of the Annals of the Four Masters, John O'Donovan, who took an interest in this sixteenth century genealogical controversy believes that the Kellys of Dundalk may have been descended from the O'Kelly kings of Brega 'and consequently [were] of as royal lineage as the O'Neills themselves, if not more so', although by the sixteenth century the O'Kellys of Brega had long been dispossessed by the Anglo-Normans who settled the Pale, and had forgotten all the history of their family and origins. O'Donovan also believes that Shane O'Neill 'proved in England that [Ferdoragh] was not [an O'Neill]'.
During the 1550s Shane O'Neill showed himself to be the first Gaelic Irish chieftain with the military skill to defeat sixteenth century English forces in battle. In 1552 Shane launched a surprise attack one night on Ferdoragh's camp 'and he routed them before them, and slew great numbers of them'. In 1558 Shane's men managed to kill Ferdoragh. The Annals of the Four Masters record that 'the cause of his killing was because he was appointed to the dignity of his father, if his father should die before him'. An English account of the killing of Ferdoragh states that he was staying one night in a castle, which Shane O'Neill's men secretly surrounded. When Shane's men shouted 'hue and cry at the side of [the] Castle', Ferdoragh was killed when he 'ran suddenly forth to answer the cry'.
A feud then developed between Shane O'Neill and the sons of Ferdoragh O'Neill. On 12 April 1562, while Shane was on his famous visit to the Court of Queen Elizabeth in England, his 'Chief Governor', Turlough Luineach O'Neill received intelligence that Ferdoragh's eldest son and heir, Brian O'Neill, was travelling between Newry and Carlingford with only a few companions. Turlough O'Neill immediately gathered a force of '100 horsemen', and rode Brian O'Neill down and killed him. This feud between the two ruling branches of the O'Neills of Tyrone continued long after Shane O'Neill was assassinated in 1567. In 1590 Ferdoragh's second son, the famous Hugh O'Neill, the second earl of Tyrone, had Shane's most promising son, Hugh Geimhleach, hanged. Such was the continued respect for the dead Shane O'Neill, that his foster-family, the O'Donnellys, offered 300 horses and 5,000 cattle to Hugh O'Neill, to spare Hugh Geimhleach's life and when this was refused, the O'Donnellys forbade any locals to carry out the execution.
Therefore, I hope these few paragraphs help show how family origins and Gaelic genealogical customs in sixteenth century Ireland led to a murderous feud amongst the ruling O'Neill family of Tyrone. The introduction of English inheritance rules played a great part in this and it could be said that a genealogical controversy helped change the course of a part of Irish history. Shane O'Neill's resentment at his displacement in the succession to the earldom of Tyrone, by a half-brother, who by the new rules of English primogentiture should not have been considered as their father's heir, launched an extremely destructive war in Ulster, which led to Shane becoming one of the most powerful and also one of the most ruthless Gaelic warlords of sixteenth century Ireland. The spread of English influence into the Gaelic Irish province of Ulster was largely halted for an entire generation and when the English finally did conquer Gaelic Ulster in 1603, it took them many years of all-out warfare, tens of thousands of soldiers and so much treasure that it almost bankrupted the Elizabethan English state. This is why the story of Ferdoragh O'Neill and his parents, Conn Bacach O'Neill, the earl of Tyrone, and Alison Kelly, the blacksmith's wife from Dundalk, is such an interesting and unusual one.