In the year 1208, shortly after the Norman Invasion, in the Territory of CENEL CONAILL (Tyrconnel), now Donegal, there was a sub-chieftain of the Clann O'Dochartaigh (O'Doherty Clan) named Daibheid O'Dochartaigh, a name meaning 'obstructionist,' who was killed in battle in the Lagan Valley, defending against an incursion by elements of the Clann O'Cahan (O'Kane Clan) and the Clann O'Neill (O'Neil Clan). There is little else known about the man, except that he was highly esteemed, fought valiantly, and died with honor. He is reported to have had six sons (no mention was made then of daughters) who were thereafter accorded the honor of being known as Sons of David , or MacDaibheid. Daibheid is the Gaelic form of the Hebrew name David, meaning beloved. In that same period, and according to a map of Ireland, circa 1200, the O'Doherty Clan was regarded as a clan of Lesser Dynastic Surname, shown in the Territory of Inis Eogain, now known as the peninsula of Inishowen.

          Although the people of the O'Doherty Clan, and their outgrowth MacDavitt Clan, were in 1608 scattered throughout Donegal in general, and the Inishowen Peninsula in particular, most lived in and around the town of Derry, at the confluence of Lough Swilley and Lough Foyle, and the center of commerce. And residing there too was the leadership both of the O'Doherty and the MacDavitt clans. Certainly predominant was the O'Doherty Clan, but the two were very close, and indeed almost as one. Not surprisingly, there was a significant British presence there, under the leadership of Governor Sir Henry Docwra. the British aim had been to break up the clans, and their success in Donegal at that time is quite apparent. But the British governor and the Lord of Inishowen had reached an entente cordiale, and indeed there seems to have been a close friendship. And yet, Sir Henry was indeed liege lord, and in keeping with aristocratic customs of the day, it was not unusual that the heir to the lordship of Inishowen be brought into his household for education and training. It was most commonly on the youth's fifteenth birthday that advisors to the head of the Irish clan would formally name him as heir, and it was soon following that occasion in1601 that Sir Cahir O'Doherty would join other such youths, to study debate, rhetoric, Latin, and other scholarly pursuits, in the household of Sir Henry Docwra.

          Conflict arose in 1607 in Ireland. The Flight of the Earls brought many changes. For one thing, Sir Henry Docwra was posted to military duty, in pursuit of the O'Neills, down toward County Louth, and was replaced as governor by Sir George Pawlett, who felt nothing but enmity toward the O'Doherty Clan. For another, it seems apparent now that the Lord of Inishowen died, and in early 1608 the twenty one year old Cahir O'Doherty was named Lord of Inishowen.

          Sir Cahir O'Doherty was godchild to the Chief of the MacDavitt Clan, Sir Phelim Reagh MacDavitt and his wife Lady Catherine. Following his father's death Cahir became foster brother to the six MacDavitt sons. (It should be noted that the story first of David O'Doherty having six sons, and then Sir Phelim MacDavitt also having six sons should be viewed with question.) Whether being godchild to the MacDavitts and foster brother to their sons involved living with them, or they with him, is uncertain, but that the MacDavitt sons and young Cahir were frequently in each other's company seems evident. However, it seems evident, too, that Sir Cahir was keenly aware of his exalted clan lordship. He knew that he owned Inishowen.

          Sir George Pawlett, had no respect for the rights or prerogatives of the youthful, and perhaps headstrong, Sir Cahir, as he laid a clever plan to strip the Lord of Inishowen of his land and holdings. For a beginning step, he arbitrarily deeded the western half of the peninsula to Sir Arthur Chichester, and then let the fact be circulated. As he no doubt expected, the word quickly reached Sir Cahir, who went raging into the governor's office, in Derry.  There an angry altercation reached a fateful ending when Governor Sir George Pawlett, surrounded by his lieutenants, struck the young man, sending him to the floor. Sir Cahir rose and angrily fled to the outside, to be met there by his six foster brothers, the MacDavitts, and by a number of youths of the O'Doherty, O'Donnell and O'Neil clans. Together they retired from Derry to lay their plans, and in the morning they affected an attack upon the town that resulted in its total destruction. Derry Governor Sir George Pawlett was sought out and killed by a man named Owen O'Doherty. The British declared that Sir Cahir's uprising legitimized the governor's awarding of a portion of Inishowen to Sir Arthur Chichester, and then trumped their own move by awarding the rest of it to him.

          But now the chase was on to capture not only Sir Cahir but the Lord of the MacDavitt Clan, held also to be responsible for the attack. Sir Cahir and many of his supporters fled to the west toward his holdings at Kilmacrenon. (Some research credits Phelim MacDavitt with ownership of castles at Kilmacrenon and Aileach. Two conflicting reports have the swords both of Sir Cahir and Sir Phelim being found at Kilmacrenon.)  Sir Cahir was captured near Kilmacrnon and executed by hanging, just as Sir Phelim MacDavitt was at Lifford, in the southernmost tip of County Donegal.

        The execution of Sir Phelim Reagh MacDavitt was, not uncommonly for its time in history, brutal. He and his wife Catherine and their sons fled south from Derry. If they had a planned desitnation it is not known, but when the family reached Lifford, a small town at the southernmost point in Donegal, Sir Phelim was taken into custody, and brought before the Crown's Lord Magistrate for trial. An account of Sir Phelim's trial was contained in a booklet published by the Christian Brothers, for use in teaching Irish history. The story presented by them may have been embellished according to the model of Irish heroism and Christian martyrdom that they wished to impart to impressionable students. Here, unable to separate actual fact from embellishment, the Christian Brothers booklet is presented in its entirety: