By John O'Donovan, L.L.D., M.R.I.A.
Taken from Duffy's Hibernian Magazine, Volume 2, 1861.
THIS famous sept, now so numerous in Ulster and Meath, derive their name and descent from Raghallach, (son of Cahalan, son of Daveron, son of Maelmora,) the eleventh in descent from Fergus, (who died in 517,) great grandson of Duach Galach, king of Connaught, the common ancestor of the O'Conors, O'Rourkes, and O'Flahertys of Connaught. Camden says that in his time the O'Reillys represented themselves as descended from the English family of Ridley, but that they were entirely Irish in their manners. It is a very strange fact that, in Camden's time, several English writers and map-makers attempted to prove, that some of the most distinguished of the native Irish chieftain families were of English descent. The object of this, no doubt, was, to make their disloyalty and rebellions appear the more unnatural. Thus, Spenser asserts, and attempts to prove by etymologies, that the Byrnes, Tooles, and Kavanaghs of Leinster, were of British descent; that the Mac Mahons of the county of Monaghan were descended of the de Veres of England! Sir George Carew states that Mac Davymore, or Mac Damore, of the county of Wexford, (who was really the senior of the Mac Murroughs of Leinster,) was descended from the Barrys; and on some maps of the county of Clare, the Mac Namaras are represented as Mortimers!!
That some of the O'Reillys who had submitted to the English in Camden's time, represented themselves as of English descent, is very possible: for it is a fact, that some of the sept settled in England at the present day, state that their name is English, and that it is the name of a place, formed from the English words rye and lea, like Wheatley, Ashley, Oakley, Cowley, Oxley, &c.; but this is no proof of their English origin. The name is not Ridley, or Ryley, nor even Rawleigh, or Raleigh, but O'Raghallaigh, i.e., descendant of Raghallach.
That the O'Reillys of Brefney never regarded themselves as of English descent, appears from the oldest genealogical Irish books and annals, in which they are called Muintir-Mailmordha, and represented as of the same race as the O'Rourkes, i.e., of the race of Aedh Finn, who was the fifth in descent from Duach Galach, king of Connaught, who was converted by St. Patrick, and died A.D. 463. From Brian, the father of Duach Galach, all the Ui-Briuin sept are sprung, and the O'Rourkes, and O'Reillys, and their co-relatives, are frequently called Ui-Briuin Breifne, the name of their territory being added to distinguish them from various other septs ot the descendants of this Brian, who were seated in other parts of Connaught.
Their early history is rather copiously given in the Annals of Ulster and of the Four Masters; but from the commencement of the reign of James I. of England, we must collect their history from various other sources. The heads of this sept were chiefs or princes of the territory of East Brefney, often called Brefney-O'Reilly, to distinguish it from West Brefney, O'Rourke's country, which was usually called Brefney-O'Rourke. East Brefney was nearly coextensive with the present county of Cavan.
To follow the Irish genealogists and annalists in their extraordinary minute notices of this family, would occupy more space than we can afford. The following details, of the ancient prominent characters of the family, will give the reader an idea of their early importance, and convince him that they are not Ridleys.
They built the castles of Tullymongan, Tullyvin, and took by force from the Red Earl of Ulster, the castle of Lough Oughter  which still remains in good preservation, A.D. 1128. At the battle of Ardee, fought between Conor Mac Loughlin, king of Ailech, and Tiernan O'Rourke, prince of Brefney, Cathal O'Raghallaigh [Cathaldus Ragallides, or Charles O'Reilly] was slain. Surely there were no Ridleys in Ireland at this early period.
A.D. 1154. Murtough Mac Loughlin, king of Ailech, banished Godfrey O'Reilly into Connaught, A.D. 1155. Donough O'Carroll, who was imprisoned by O'Rourke in an island in Lough Sheelin, was set at liberty by Godfrey O'Reilly. A.D. 1157. Donnell O'Reilly was slain by the Galenga. A.D. 1160. Godfrey O'Reilly was slain at Kells by Melaghlin O'Rourke, who also slew Gilla Isa O'Reilly, the son of the said Godfrey, on the following day.
A.D. 1226. The castle of Kilmore, [erected by the English,] was demolished by Cathal O'Reilly. A.D. 1231. O'Donnell led his forces against Cathal O'Reilly, and plundered the island of Eo-inis, in Lough Oughter, in which O'Reilly had his treasures. A.D. 1233. William, son of Hugh de Lacy, marched an army into Brefney against Cathal O'Reilly.
A.D. 1237. Clarus Mac Mailin, under the patronage of O'Reilly, erected a monastery for canons regular on Trinity Island, in Lough Oughter. A.D. 1256. Cathal O'Reilly, Lord of Muintir-Mael-mora, and of all the race of Aedh-Finn, was slain by Hugh, son of Felim O'Conor, king of Connaught. AD. 1330. Gilla-Isa Roe O'Reilly, Lord of all Brefney for a long time, died at an advanced age, victorious over the world and the devil, and was interred in the abbey of the friars minor, at Cavan, of which he himself was the founder. In the same year was slain Niall Caech O'Reilly, ancestor of the Clannkee.
When Edward II., in 1314, sought the aid of the Irish chieftains, he directed a special letter to this "Gillys O'Raghli Duci Hibernorum de Brefney."
These notices are presented to the reader to satisfy him that this family is not of English descent. But to follow the Irish annalists in their various minute notices of this family, would occupy too much space for a publication of this kind, and we shall therefore begin our regular history of the O'Reilly sept, with the stirpes of the most famous branches, who still reflect honour on their ancestors.
Their territory of East Brefney is celebrated in the history of the wars in Ireland for the fastnesses formed by its woods, lakes, and bogs, which long secured the independence of its native chieftains. It was formed into the county of Cavan by Sir John Perrott, Lord Deputy of Ireland in 1584, and placed in the province of Ulster, though it had belonged to the province of Connaught in ancient times. The O'Reillys were at this time a very warlike sept, and particularly distinguished for their cavalry, not living in towns, but in small castles scattered over the country. In order to weaken their power by dividing the territory among different leaders, and thus make them obedient to English law, it was resolved to divide it into baronies, and settle the proprietorship of each exclusively on a separate branch of the family of O'Reilly, as will appear from cotemporaneous documents to be quoted presently.
The chief river of this territory is the Erne, which rises in a well near Lough Gowna, on its south-western confines, whence it flows in a northern course into Lough Oughter, and thence winds its course in the same direction by Belturbet into Lough Erne, which at its head forms the northern limit of this territory. Its other waters consist of numerous small lakes, and their connecting streams, which are, with few exceptions, tributary to the Erne. The Shannon, the giant of Irish rivers, has its source in this territory, in a deep spring called the Shannon Pot, situate near the foot of the Quilka mountain, in the district of Glen Gavlin. From this spot to Kerry-head, where it falls into the sea, it pursues a course of 243 miles. The Blackwater has its source in a lake at Bailieborough, and flows on by Virginia into Lough Ramor, whence it enters the county of Meath, and becomes a tributary to the Boyne.
The remains of antiquity in this territory are very few indeed; and there is no other territory of equal extent and ancient importance in Ireland which possesses so few. The most common are cairns and raths, the latter of which are numerous in the north-eastern part of the territory, where the natives remark that they are always in straight lines, and visible from each other. There is a remarkable one called Rathkenny, near Cootehill, in which it is said a crock of gold and some gold ornaments were found. There are remains of a round tower at Drumlane, built of limestone, and red grit, exhibiting sculptured on a stone the figure of a cock, which is evidently very ancient; the church of Drumlane scarcely retains a feature of ancient architecture. Of the eight abbeys recorded to have been erected in this territory, no remains now exist, with the single exception of that of the Holy Trinity. Their sites only are traceable. The oldest, which is Snamhluthair, now Slanore, near Kilmore, is level with the ground. Of the castles of the O'Reillys very few remain. They are all small and uninteresting, except that called the Clough of Lough Oughter, in which the famous Owen Roe O'Neill died in 1649, and which is still in good preservation. The great castle of Tullymongan, the residue of the chiefs of Brefney for many centuries, and the great abbey of Cavan, are level with the ground, and their sites only are pointed out. Another curious fact worth mentioning is, that while the O'Reillys are still the most numerous sept in the whole territory, there is not a single man of the name who owns an acre of it by hereditary descent, or, we believe, by purchase.
The stirpes of the families of this sept, whose pedigrees are known, was John (son of Cahal) O'Reilly, chief or prince of Brefney, who died in the year 1510. He was the first who established the friars of the Strict Observance in the monastery of Cavan. He had three sons: 1, Ferral O'Reilly, who succeeded him as prince of Brefney, and died in 1536. 2, Cahir Moder, who was slain in 1537, and Maelmora, or Myles O'Reilly, who continued the race. Ferral had a son, Brian, who was elected prince of East Brefney, but was killed by the English in 1537, leaving no issue. Maelmora then became the O'Reilly, and married Margaret, daughter of Hugh Duff O'Donnell, prince of Tirconnell, and he had by her (she died at a great age in 1582) Hugh Conallagh (i.e., Hugh of Tirconnell, so called because he was fostered in his mother's territory), and Edmond of Kilnacrott, besides Cahir, Owen, and Thomas; of whose descendants nothing is known. Hugh was inaugurated chief of East Brefney, and Edmond was at the same time appointed his Tanist. Hugh married Isabella, daughter of Beatty of Moynalty, and had by her three sons: Shane Roe, afterwards Sir John O'Reilly, and also Philip, Owen, and Maelmora; and four daughters, who were married to four respectable chieftains. These genealogical details are absolutely necessary to enable the reader to understand the nature of the struggles which soon after followed between the rivals of this family.
Hugh Conallagh O'Reilly died in the year 1583, after which Edmond of Kilnacrott, the Tanist of Brefney, claimed to succeed next as chief of Brefney, according to the Irish custom of tanistry; but Shane, or John Roe O'Reilly, the son of Hugh Conallagh, successfully opposed him. In the year 1585 this Edmond O'Reilly, the Tanist of Brefney, and Philip, one of his nephews, were elected to represent the county of Cavan in Perrott's parliament of 1585; at which Shane Roe also appeared, claiming the chieftainship of Brefney, in preference to his uncle Edmond. The Dublin parliament, however, did not decide this dispute, and John O'Reilly repaired to England to solicit Queen Elizabeth's interest. He was honourably received at court, and invested with the order of knighthood. Overcome by such royal favour, he became one of the loyalest subjects in Ireland, and attempted to get the whole of Brefney passed to him and his heirs under the crown of England, but in this he was powerfully opposed by his relatives, who conceived that they had as good a right to their respective shares of the territory of Brefney as he had.
The Four Masters record the death of his father, Hugh Conallagh, as follows, at the year 1583:
"O'Reilly (Hugh Conallagh, son of Maelmora, son of John, who was son of Cathal),. a man who had passed his time without contests or trouble, and who had preserved Brefney from the invasions of his English and Irish enemies, as long as he lived, died, and was buried in the monastery of Cavan. His wife, Isabella Barnewall, died about the same time. The son of this O'Reilly, namely, John Roe, then exerted himself to acquire the chieftainship of the territory through the power of the English, in opposition to Edmond, the son of Maelmora, who was the senior according to the usage of the Irish. In consequence of this, the country and the lordship were divided between the descendants of Maelmora.
According to a manuscript at Lambeth, (Carew Collection, No. 635, fol. 19,) the territory of East Brefney was divided on this occasion between four principal men, of the descendants of Maelmora, father of Hugh Conallagh, namely: 1, Sir John O'Reilly, son of Hugh, son of Maelmora: 2, his uncle, Edmond of Kilnacrott, son of Maelmora, and who was at this time tanist of Brefney, and became chief of Brefney in 1596; 3, Philip O'Reilly, second son of Hugh Conallagh, who was elected chief of Brefney by the Earl of Tyrone, in 1596; 4, Maelmora, son of Philip, son of Owen, son of the said Maelmora. The following are the words of this MS.
"The BRENY, now called the county of Cavan, hath been, time out of mind, wholly in the jurisdiction of him that for the time was O'Reilly, that is to say, lord of the country; but when partition of the same was made by Sir Henry Sidney, then Lord Deputy of Ireland, the baronies within the county of Cavan aforesaid, were divided amongst the principal gentlemen of the O'Reillys, as ensueth, viz: To Sir John O'Reillye, and his heirs the baronies of Cavan, Tullaghgarvy, Tullyhunco, and Tullyhaw; to Edmond O'Reillye and his heirs, the barony of Castlerahin; to Philip O'Reilly and his heirs, the barony of Inniskine (now Clan-kee); to Moylmore mac-an-Prior, and his brothers, the baronies of Rathenarome" (now Clanmahon).
Sir John O'Reilly complained to the government of the division recently made of "the Brennie," on the 1st April, 1585, and commissioners were sent to Cavan to examine into the nature of his complaint. They proposed to him several queries, and his replies, which are preserved in the Carew Collection of MS. at Lambeth, No. 614, p. 162, throw a curious light on the ancient customs of this territory.
"Sir John O'Reilly, sett downe the limittes of your territories, and the baronies according to the new Indentures. Item, what rents, duties, and customes you ought to have out of every pole in the five baronies. Item, what cause of complaint you have against your neighbours, or any other in the countrie."
After describing the limits of the baronies of Cavan, Tullaghgarvy, Tullyhunco, Tullyhaw, and Clanmahon, he proceeds as follows:
"It may please your Lordship to call for Mulmore mac Prior O'Reilly (i.e. Myles, son of Philip the Prior, son of Owen, who was Sir John's uncle) of Clanmahon, who hath threatened the tenants of the said Sir John, who dwelt in the towne[land] of Dowell-Donell, and hath put them in such fear to lose their lives and goods, as divers of them have departed from the said lands, and the rest will presently depart; by meanes whereof the said landes are waste, to the greate hindrance and disinheritance of the said Sir John and his heirs, if your Lordship take not some order to the contrary, by surety of feare or good averring against the said Mulmore, which it may please you to do."
He then sets forth the duties and customs of the Brennie, as follows:
"O'Releye, by ancient custom and usage of the country, had always out of the baronies of the Cavan and Tullagharvy, and out of every of the other three baronies, which he hath lost by the late division, forty five pounds as often as he had any cause to cesse the said baronies, either for the Queen's rents and duties, or for any charge against Onele, or other matter, which sometymes was twise or thrise a yeare, and every time forty-five pounds to his owne use, besides the charge of the cess. Item, he had lykewise, by the said custome and usadge, all manner of chargis that either his son or any other of his men or followers weare put into by reson of their beinge in pledge, or attending by commandment of the Lord Deputy in Dublin, or otherwhere, for matter of the said O'Reley. Item, by the said custom O'Reley had all manner of fees, and pensions, and recompencis given by the said O'Reley to any learned counsell or other solicitor or agent, for the causes of the contry, borne and paid by the said country. Item, by the said custom O'Reilly had yearly, over and beside all other duties and customes, towards his chargis in going to Dublin, out of every pole, sixteen pence sterling. Item, by the said custom, he had yearly, out of every eight pooles through the whole fyve barronies, one fat beefe for the spendinge of his house. Item, by the said custom, he had one horse for himselfe, one horse for his wife, and one horse for his son and heir, with one boye attendinge uppon every horse, kept through the whole fyve barronies yearely. Item, by the said custom, it was lawfull for O'Rely to cess uppon the MacBradies, the MacEnroes, the Gones (O'Gowans), and the Jordans, by the space of three quarters of a yeare yearly, one foteman uppon every poole which the said sirnames had, to keepe his cattell, to reape and bynde his corne, to thrashe, hedge, and dicthe, and do other husbandry and mercenary work for the said O'Rely. Item, by the said custom the said O'Reley had upon the Bradies, the Gones, the MacEnroes, and the Jordans, out of every pole of land yearly, three quarters of a fat beefe, and out of every two poles one fatt porke, and also the cessing of strangers, their men and horses, as often as any did come in friendship to the country. Item, by the said custome the said O'Reley had by duty all manner of charges, both for workmen, stuff and labourers, and victualls, for the building and maintaining of his castell of the Cavan and all other necessary roomes and offices about the same, borne and paide by the gentlemen and others of the barony of the Cavan. The duties of the towne of the Cavan also by the said custom, as rents, drink, and other duties, now taken and not denied. Item, Sir Hugh O'Rely, father unto the said Sir John, had in mortgage from divers of the gentill of Clanmahon forty-eight poles (of land) in pawn of fifty milche kine, which mortgage descended upon Sir John, and he was seised of the said forty-eight poles untill the (late) division, which he desireth to continue possession of, or else that he may be paide the said fifty milche kine."
Sir John O'Reilly, who was loyal nearly all his life, was at length induced to join in the recently hatched rebellion of Tyrone. He died in the year 1596, leaving two sons, Maelmora and Hugh; but though the Irish custom of tanistry was then believed to be abolished for ever, Hugh, Earl of Tyrone, appointed Philip, the brother of Sir John, "prince of Brefney" in defiance of English authority. Philip had been confined in the Castle of Dublin, but escaped with the famous Red Hugh O'Donnell. Philip, however, did not live long to enjoy this dignity, for he was accidentally killed, soon after his inauguration, by Tyrone's people, upon which old Edmond the tanist was permitted to succeed, according to the Irish custom. In the meantime, Maelmora, the eldest son of Sir John, a young man of majestic personal form, and of great valour and ambition, who was married to the niece of the Earl of Ormond, placed himself under the protection of the English government, and repairing to London on his father's policy, was graciously received by the Queen, who gave him a grant of lands in the county of Cavan under letters-patent, with the promise of being created Earl of Cavan. He commanded a regiment of cavalry in the English service, and was called the Queen's O'Reilly. He was slain in the celebrated battle of Athbuidhe, or the Yellow Ford, in the county of Armagh, A.D. 1598, after having exhibited prodigies of valour, as we are informed by Philip O'Sullivan, who had received his information from eye-witnesses.
"After the fall of Marshal Bagnal," says O'Sullivan, "the rere of the army which he commanded became so dispirited as to be able to afford no assistance to the others. However, Melmorus O'Reilly, surnamed the Comely, ordered the vacillating to be of firm courage, and with him to resist the enemy; that it was better to be slain fighting and avenged, than to fall and be killed with impunity; and that it might still be possible to withstand the assault of the enemy, and mayhap repel him. Some being animated by the exhortation of Melmorus the Comely, particularly some Irish youths, his kinsmen, renew the battle. With whom, as they fought, he turned him in every direction that he might aid them in their danger and distress. But the few who remained with him being deserted by the Queen's party, and surrounded by the Irish Catholics, fall covered with wounds, and the Comely Melmorus himself, being left alone, fell fighting most valiantly."
After the fall of this comely youth, old Edmond of Kilnacrott enjoyed chief sway over Brefney till his death, which took place in April, A.D. 1601, after which Owen O'Reilly, the brother of Sir John, was inaugurated prince of Brefney, but he died in the same year, and his next brother, Maelmora, the fourth son of Hugh Conallagh, succeeded according to the custom of tanistry, and enjoyed this dignity till the plantation of Ulster, in 1609. He died in 1635, and with him ended the succession of the chiefs of East Brefney. The descendants of Sir John O'Reilly, and of his brothers and several other branches were restored to considerable tracts of land in the county of Cavan. The following persons of the name O'Reilly are mentioned in Pynnar's survey.
"1, Shane MacPhilip O'Rellie, who got nine hundred acres in the precinct of Castlerahin. 2. Mulmorie, Mac-Philip O'Reyley, a thousand acres called Iterry-Outra, in the precinct of Tullagarvy. 3. Captain Reley, a thousand acres, called Lisconnor, in the precinct of Tullaghgarvy; all his tenants do plough by the Tail. 4. Mulmorie Oge O'Relie, three thousand acres, &c., in the same. His tenants do all plough by the Tail. 5. Mulmorry macHugh O'Reley, two thousand acres, called Commet, in the precinct of Clanmahown. 6. Philip MacTirlagh, three hundred acres, called Wateragh, in the same.
In the time of King James I. Sir John Davis, the attorney-general, wrote a curious and valuable account relative to the comity of Cavan and its ancient chieftains, which is preserved in a manuscript in Trinity College, Dublin (F. iii. 16, fol. 121 et seq.) In 1606 a commission was directed to Sir Garrett Moore and others, to ascertain what lands were come to the crown in the county of Cavan; in pursuance whereof an inquisition found that Philip O'Reilly was seised in the thirty-sixth year of the reign of Elizabeth of the entire region or territory of Brefney O'Reilly, containing seven entire baronies, into which, on the day after Philip's death, Edmond O'Reilly entered, and levying open war against the queen, was also slain!! that the said Sir John O'Reilly had claimed the said country by tanistry, and was for a time received into the queen's favour, but that he adhered to Tyrone, and died a rebel.
No less than fifty-two persons of the family of O'Reilly, who were proprietors of considerable tracts of land in the county of Cavan, were attainted on this occasion. The persons enumerated by Pynnar, above quoted, were alone deemed worthy of being restored to portions of their ancient estates. This being completed, the king resolved on the new plantation of Ulster, in which the plan for the division of this county was as follows: "The entire county was estimated to contain 1620 poles of land, each pole containing twenty-five acres, in all 40,500 acres. The Termon or church lands, in the ancient division, contained 140 poles, or 3500 acres, which the king reserved for the Bishop of Kilmore. For the glebes of the incumbents of the parishes to be erected were allotted 100 poles, or 2500 acres; and the monastery lands were found to consist of 20 poles of 50,0 acres. There then remained to bo distributed to undertakers 1360 poles, or 34,000 acres, which were divided into twenty-six proportions, seventeen of 1000 acres each, five of 1500, and four of 2000, each of which was to form a parish, to have a church erected upon it, with a glebe of 60 acres for the minister in the smaller proportions, of 90 on the next, and of 120 in the largest. To British planters were granted six proportions, viz.: three of the least, two of the next, and one of the largest; and in these were to be allowed only English and Scottish tenants. To servitors were to be given six other proportions, three of the smallest, two of the middle, and one of the largest, to be allowed to have English or Irish tenants at choice; and to natives the remaining fourteen, being eleven of the least, one of the middle, and two of the greatest size. There then remained sixty poles, or 1500 acres, of which thirty poles, or 750 acres, were to be allotted to three corporate towns or boroughs, which the king ordered should be endowed with reasonable liberties, and send burgesses to parliament, and each to receive a third of this quantity; ten other poles, or 250 acres, were to be appendant to the castle of Cavan; six to the castle of Cloghoughter, and the remaining fourteen poles, or 350 acres, to be for the maintenance of a free school, to be erected in Cavan. Two of the boroughs that were created, and which received these grants, were Cavan and Belturbet, and the other 250 acres were to be given to a third town, to be erected midway between Kells and Cavan, on a site to be chosen by the commissioners appointed to settle the plantation. This was Virginia, which, however, was never incorporated.
The native inhabitants were awed into acquiescence in these arrangements, and such as were not freeholders under the above grants, were to be settled within the county, or removed by order of the commissioners. The lands thus divided were the then profitable portions, and to each division a sufficient quantity of bog and wood were superadded. A considerable deviation from this project took place in regard to tythes, glebes, and parish churches.
A curious record of the progress made by the undertakers in erecting bawns, or fortified houses, up to the year 1618, is preserved in Pynnar's survey, published in Harris's Hibernica. The number of acres enumerated in this document amounts to 52,324 English measure, and the number of British families planted on them was 386, who could muster 711 armed men. Such was the foundation of the modern rights of property in the county of Cavan. It did not, however, remain long undisturbed, for the head of the O'Reillys, who was representative of the county in parliament, and his brother, who was the high sheriff, were deeply engaged in the great rising of 1641. The sheriff summoned the native Irish to arms, and they marched under his command with considerable discipline. Forts, towns, and castles were surrendered to them, and Bedell, the Protestant bishop of Kilmore, was compelled to draw up their remonstrance of grievances to be presented to the chief governors and council.
Sir John O'Reilly had a younger son, Hugh O'Reilly, who had a son, Colonel Philip O'Reilly, who in 1635 resided at Ballynacargy Castle, in the county of Cavan. This Philip was the head of the O'Reilly family just referred to. When a young man he served for some time in the Spanish army, but returned to Ireland previously to 1641, and became one of the chief leaders during the great rising of that year. He raised a brigade of twelve hundred men, composed chiefly of his name and family, and served with distinction as lieutenant-general in the service of the confederate Catholics of Ireland, He married Rose, the sister of the famous Owen Roe O'Neill, and co-operated with that leader. He was attainted in 1642, and again in 1652, further denounced by Cromwell's act. Being then obliged to expatriate himself, he retired with his brigade into the Netherlands, where he served in the Spanish army for about three years, when he died, A,D. 1655, and was buried in the Irish monastery at Louvain. His only son, Hugh Roe O'Reilly, by his wife Rose O'Neill, was slain by the Parliamentary forces in Cavan, in the year 1651, leaving by his wife, Margaret, daughter of Conor O'Brien, Lord Viscount Clare, an only son, Huge Oge O'Reilly, who was drowned on his passage from Spain, and in him the race of Colonel Philip, the grandson of Sir John O'Reilly, became extinct.
Colonel Philip had a younger brother, Maelmora or Myles, who had a son, Edmond Boy, who was considered the chief of the O'Reillys. He went to France in his youth, and served there in the king's life-guards, but returned to Ireland in 1688, with King James II, by whom he was appointed colonel of infantry, and lord-lieutenant of the county of Cavan. He was present at the sharp encounter which took place between the Duke of Berwick and Colonel Wolsely, in which a lieutenant-colonel, a major, and a captain O'Reilly were slain. Colonel Edmond Boy O'Reilly subsequently distinguished himself at the Boyne, at Limerick, and at the second siege of Athlone. In 1691 he was governor of Lanesborough, and when Wauchop, the governor of the castle of Athlone, had learned that De Ginkell intended to cross the Shannon, he gave warning to O'Reilly, directing him, in case of any danger, to send for the Earl of Antrim's regiment, which was ready to advance on the first signal for Lanesborongh, and to drive the English into the river. Colonel O'Reilly accordingly threw up strong works in the only accessible part of the bank, at the Connaught side of the river, which caused De Ginkell to abandon the idea of crossing over at that point. At the time of the surrender of Galway, in July, 1691, Colonel O'Reilly was in the town, and was one of the hostages for its due surrender; and in its articles of capitulation, a special protection was inserted for his wife's mother and family, then residing in the town with him; a similar protection being also given to his brother, Lieutenant Luke O'Reilly, and his family.
After the capitulation of Limerick, Colonel O'Reilly and many of his own regiment retired with the Irish refugees to France, where he died in 1693, leaving, by his wife Joane, daughter of Brian Offerrall of Moate, in the county of Longford, an only son, Owen, who, on his father's decease, entered into Dorrington's, afterwards Dillon's Brigade, and married, at St. Germains, the daughter of Colonel Felix O'Neill, (who was killed at Aughrim,) and died in 1735, leaving a son Edmond O'Reilly, born in 1722, who entered the Irish brigades in four years after his father's death. He was a captain in Lally's regiment in 1757; in the following year he was created Knight of St. Louis; in 1763 he was a captain in Dillon's regiment; in 1773 ranked as a retired lieutenant-colonel, and was living in Paris at the commencement of the French Revolution. This is the last of the race of Sir John O'Reilly that has been heard of by any of our historians or genealogists.
 The writer was acquainted with a visionary Irish etymologist, who believed that Sir Thomas More, Lord-Chancellor of England, as well as Thomas Moore the poet, was descended from the O'Mores of Leix, and Sir Walter Raleigh from the O'Raghallaighs (O'Reillys) of Brefney. This is barely possible, but no proof of the fact has been yet adduced. Colgan preserves the ancient form of this name in the dedication of his Acta Sanctoram, in 1645, Illustrissimo et Reverendissimo Domino D. Hugoni Ragallio, Ardieopiscopo Ardmachano, Hibierniae Primati, &c.
O'Dugan, in his topographical poem, describes O'Reilly thus:--
"Righ-thighearna na ruathar n-garbh
O'Raghallaigh na ruadh-arm,
Do cluintear aoibh a orghuth
Os Muintir Maoil-min-Mordha."
"Royal lord of rough incursions,
Is O'Reilly of red weapons;
The deliciousness of his golden voice is heard
Over the polished Muintir-Mealmora."
 The castle of Tullymongan, O'Reilly's chief residence, stood in a townland of the same name, on the east side of the town of Cavan. The foundations of this castle are now scarcely traceable. In the year 1400, John, son of Philip, and the grandson of Gilla Isa O'Reilly, died in this castle, as did Turlough, son of John, son of Owen, in 1487.
 The castle of Lough Oughter is called Cloch Locha Uachtair (i e. the rock of the upper lake) by the Irish annalists. It is a round castle of considerable strength, situated in Lough Oughter, near Kilmore, on a small island, said to have been formed by dropping stones into the lake. The writer examined this castle in May, 1836, when it was in good preservation. It is like Reginald's Tower at Waterford; the Tower of Hook in the county of Wexford; and the keep of the Castle of Dundrum, in the county of Down. In the year 1327 this castle was taken by Cathal O'Rourke from the O'Reillys. In 1369 Philip O'Reilly, lord of East Brefney, was imprisoned, and severely bound and fettered in this castle by his rival Manus O'Reilly. In the next year Manus O'Reilly was in his turn taken and imprisoned in this castle.
 The Clann-Kee O'Reilly gave name to the barony of Clankee, in the east of the county of Cavan. All the families of this sept had taken the name of MacKee, but they were compelled to reassume their true name, O'Reilly, by the celebrated Hugh O'Reilly, Primate of all Ireland in 1645.
 " Melmorrus, Orelli principis filius, ob raram staturae elegantiam, et miram, faciei venustatem cognomento Pulcher."--P. O'Sullivan Beare.
 The death of this Edmond O'Reilly of Kilnacrott is entered in the Annals of the Four Masters as follows:--"A.D. 1601. O'Reilly, i.e. Edmond, son of Maelmora, son of John, son of Cathal, died in the month of April. He was an aged, grey-headed, long-memoried man, and who had been quick and vivacious in his mind and intellect in his youth. He was buried in the Franciscan monastery at Cavan; and his brother's son, namely, Owen, son of Hugh Conallagh, was elected in his place."
 Mr. O'Callaghan, in his Irish Brigades, vol. i., p. 274, states, on the authority of information furnished by a Mr. O'Reilly, of the Antilles, to M. de la Ponce, that he had another son, Philip O'Reilly, who went to Scotland to support the cause of Prince Charles Edward Stuart, where he fell into the hands of the enemy, and was burned alive.