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Elagh Castle

Elagh Castle, was the historic seat of the Ó Dochartaigh power during our rule of Inishowen. It was both the principal castle and primary residence of our chieftains and was during its heyday probably the most impressive fortification in Inishowen. While today there is little remaining but one ruined outer tower which is often referred to as Doherty Tower, recent archaeological excavations have renewed the sites’ historic association with Aileach, the early medieval royal site of the Cenél nEógain which pre-dates the Ó Dochartaigh occupation of Inishowen.

Elagh Castle: The O'Dochartaigh Seat of Power

Archaeologists believe that Elagh Castle has undergone a number of phases throughout its existence. While many Ó Dochartaigh fortresses were constructed during the 15th and 16th centuries, archaeologist agree that the masonry from remains of Elagh’s present phase appear to be of 14th century construction. The Annals indicate that when Domnall Ó Dochartaigh died in 1339, “there was little wanting from his having the lordship of Inis-Eogain”. Complete lordship of Inishowen was in Ó Dochartaigh hands no later than the death of Conchobur Ó Dochartaigh in 1413. As the ruins we see today are believed to have been built during the 1300s, we’re not sure if the Ó Dochartaighs were the original builders of the structure we see today or if it was built under Ui Neill control. Either way the Ó Dochartaighs likely continued to change the footprint and face of the structure as time continued. Queens University Belfast’ archaeologist Cormac McSparron mentioned that Elagh has an inner masonry skin which was later covered over by an outer layer which changed the appearance of the original structure. 

The bardic poem of Tadhg Dall Ó Huiginn, titled “Inishowen”, composed between 1550–1591, praises the our Chief, Sir John, as “O'Doherty of the castle of Oileach” (Aileach/Elagh). A letter dated 1588 from Richard & Henry Hovenden to the Lord Deputy of Ireland mentioning a “village of Sir John Ó Dogherty, called Illagh”, as well as one of Docwra’s maps of Derry circa 1600 mentioning both a castle and a town at Elagh, indicates the site was well developed by the late 16th century.

When the English landed in Inishowen and began their military campaign in 1600, Sir John Ó Dogherty and the villagers at Elagh abandoned the site. Sir Henry Docwra wrote that “We marched to the castle of Ellaughe, Ó Dogherty's chief house, and there finding it broken in some part, all the town burnt, and by them quitted”. He indicated in his Narration that “Sixe days wee spent in labour about it, in which meane space, making upp into the Countrie with some troupes (onely with intent to discover) we came to Ellagh a castle of the Ó Dogherty's, which had yet newlie abandoned and begunne to pull down, Butt seeing it yett Tennable and of good vse to be held, I put Captaine Ellis ffloudd into it and his companie of 150 men”. It was by the early part of the next year that Sir John Ó Dogherty had died, having forfeit Elagh and his other lands when he rebelled against the English.

In 1603, Sir Cahir Ó Dogherty was regranted much of the Ó Dochartaigh ancestry lands including Elagh and he resumed Ó Dogherty occupation of Elagh Castle. It was there that he summoned Captain Hart to dinner and lavish entertainment before he captured Hart’s Fort Culmore the first night of the Ó Dogherty Rebellion in April 1608. In July 1608, after the rebellion, Sir Thomas Ridgeway wrote that, “they went to the traitor's castle and town of Elough which, though strong by situation and by extraordinary thickness of wall and bawn about it, they found (contrary to their expectations) evacuated”. Sir Cahir’s grant of lands, including the Castle Elagh, was revoked upon his rebellion and subsequent to his death were regranted, along with the rest of Inishowen, to Lord Deputy Arthur Chichester. Chichester used Elagh as a garrison, but then leased it out by 1621. The castle had falled into disrepair before 1665.

Elagh Castle: The Site of the Ancient Royal Seat, Aileach

The fortress of Aileach was mentioned in historic references particularly as being enclosed within a wall. During the 1830s, several historians were attempting to make sense of these historic descriptions of Aileach and began associating the historic royal seat Aileach with An Grianán atop Greenan Mountain a few miles from Elagh. This association was due to the fact that An Grianán remained a considerably impressive structure surrounded by its massive wall, while at Elagh was only the ruined remains of one tower which appeared to be of more recent construction than the legendary Aileach was supposed and also had no existing walls. This change of associating Aileach with An Grianán rather than Elagh was met with controversy at first, but over time became more widely accepted. Modern examination of historical texts, along with archaeological digs, however, have reversed the 19th century rewrite of history giving back Elagh its proper prominence as the royal site of Aileach.

Historic Inishowen was divided into three kingdoms. Aileach was the royal seat of the southern kingdom and the name of their kingdom it ruled. An Grianán does not seem likely as the the original site of Aileach as it was outside the borders of Inishowen and the historic kingdom of Aileach—being separated from it by a nearly impassable bog. Furthermore, the very townland Elaghmore and the name of the ruins within it, Elagh, are anglicizations of the Irish word Aileach, which have persisted through medieval times to today.

Aileach, whether the royal site or its surrounding kingdom, is mentioned in the historic Irish Annals and poems throughout the middle ages, either as a location or in reference to her kings. There was mention of Aileach’s destruction in the year 676 AD, it’s sacking in 900 AD by "foreigners", a Viking raid in 939 AD during which her king was captured, and a mention that the site was razed and dismantled in 1101 AD by Muircheartach ua Briain. There are, however, references to Kings of Aileach up until 1251. Scholars believe the Ui Neill transitioned away from that title because the desired to be styled as “Kings of Ulster” as they continued to rise in power. Many old writers assumed the destruction of Aileach in 1101 AD was the end of Aileach altogether, however, modern scholars believe the site was repaired and continued to exist regardless of whether it remained the royal seat of the Cenel nEogain.

The Origins of Aileach are shrouded in legends which indicate it may have been the site of an ancient megalithic tomb associated with the Tuatha de Dannan. Legends continue with the site being the fortress of a Pict and his lover Aileac, a Scottish kings’ daughter who fled their land. Later mention indicates it was a stronghold of the Ulaid kingdom which was conquered by the Three Collas. Legend has it that Eoghain, son of Niall of the Nine Hostages, captured Aileach during the 5th century and it was blessed as his abode by St. Patrick. Such references reveal that Aileach was early on associated with the Ui Neill and indicate that if it was not constructed by them was certainly captured by their force.

Tadhg Dall Ó Huiginn’s 16th century poem of praise for our Chieftain, Sean Ó Dochartaigh (Sir John Ó Doherty), mentions Aileach a number of times, gives its history, associates it with Elagh Castle, and indicates that the Ó Dochartaighs were ennobled by their possession of this historic site.

Historical & Archaeological Descriptions of Elagh

Elagh Castle was perched atop a mound-like outcrop of Dalradian schist that stood preeminently above the surrounding countryside commanding good views to the east and west, as well as southward toward Derry and the historic bogs which marked the southern border of Inishowen. The oval-shaped prominence of bedrock upon which the stronghold was situated rises roughly 10 feet above the nearby terrain and measures approximately 80 feet north-to-south and 115 feet east-to-west.

During summer 2013, a large community archaeological dig was carried out at Elagh under the oversight of Queen's University Belfast’s Center for Archaeological Fieldwork. Archaeological excavations revealed that Elagh was at one point enclosed by a ditch and stone-faced bank which extended a considerable distance from the castle and is believed to date from the early medieval period. There is evidence of an even earlier enclosure in the form of holes from posts and stakes that were buried beneath the earthen bank. This, along with various artifacts uncovered reveal that the site at Elagh dates to a much earlier time than previously imagined and is one of the main arguments for its re-association with historic Aileach.

The excavation also uncovered traces of ancient walls, paved areas with stones which may have been part of another structure, and evidence of a defensive bawn wall. The report from the archaeologists indicated the bawn wall or what “seems to be a very large early Medieval enclosure around Elagh Castle matches well the ‘the hero’s rath...’ mentioned in the Metrical Dindshenchas”. Finally, masonry found in one trench agrees with the 17th century letter of Sir Thomas Ridgeway mentioning the “extraordinary thickness of wall and bawn” around Elagh.

Today, the only prominent remains of the once-imposing fortress are the ruins of a tower roughly 20 feet wide, 6 feet thick, and 26 feet high with hints suggesting battlements, a staircase, and attached structures. Some scholars interpret the architecture of what little remains to suggest the tower was one of a twin set of English-style “D” shaped towers between which was the gatehouse. This architectural interpretation seems to fit with the political landscape of the time and the site’s association with the Ui Neill—suggesting Elagh may have been the prototype for Harry Avery's Castle.


Ó Huiginn’s poem, referenced earlier, says Elagh had a “labyrinthine (?) four-towered court.” This agrees with Ashby’s Map from circa 1600 which contains a drawing of Elagh showing a large two-story keep enclosed by curtain wall or bawn with four semi-circular towers projecting from two sides of the bawn. The maps indicate there were earthenworks just outside the bawn and a wooded area. Ashby's map and King James’ Irish Patent Rolls indicate that there was a paved roadway or "causey" approaching Elagh Castle. Being as this was the seat of Ó Dochartaigh rule and well as of the Ui Neill, it's sad that there is so little remaining of the structure.

Click the thumbnails below to open the photos in a larger viewer!

Other Resources to Check out

This comprehensive 84 page PDF contains references to Elagh in the Annals and other Irish literature, maps, archives, a history of previous archaeological excavations, as well as the findings, artifacts, trench cross-section diagrams, and photographs of the dig by Queens University.

Visiting Elagh

The ruins of Elagh Castle, known locally as Doherty’s Tower, are located behind some farm buildings on Upper Galliagh Road in the townland of Elaghmore, a little over 3 miles north historic walls of Derry / Londonderry. There are several Bed and Breakfasts which employ the name Elagh, within a few rock’s throws from the site in this lovely agrarian suburb of Derry. This is not a major tourist attraction, as can be seen by the scarcity of pictures of the structure. As the remains are in the middle of a farm, please seek permission if you need to cross private property.



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