The Battle of Farsetmore is fought near Letterkenny in County Donegal, on May 8, 1567, between the O’Neill and O’Donnell Túath. Shane O’Neill, chief of the O’Neills of Tír Eoghain, is defeated by Aodh mac Maghnusa Ó Domhnaill (Hugh O’Donnell) and the O’Donnells free themselves from O’Neill aspirations of ruling Ulster as its King.

Shane O’Neill had, in the previous 20 years, eliminated his rivals within the O’Neills and asserted his authority over neighbouring clans (or “septs“) the MacDonnells of Antrim in battle and O’Donnells by kidnapping the O’Donnell leader Calvagh, in Donegal. In 1566, the English Lord Deputy of Ireland, Henry Sidney, gives support to the O’Donnells by ransoming the long tortured Calvagh O’Donnell, against O’Neill who is regarded as a destabilising and anti-English power in the north of Ireland. O’Neill forces out these English troops, but the new O’Donnell chieftain, Hugh O’Donnell, who takes over after the long tortured Calvagh dies, takes the opportunity to assert his independence and raids O’Neill’s lands at Strabane. In response, O’Neill musters his armed forces and marches into O’Donnell territory.

O’Neill crosses into Tir Connell (O’Donnell territory) the traditional way by crossing the River Swilly at an Fearsaid mhór (known as Porterfields today), about 3 km (2 miles) east of the modern town of Letterkenny. O’Donnell has advance warning of this impending incursion so has prepared for the forthcoming attack by dispatching messengers to all his people. Both sides are not equal in size. O’Neills army is estimated at 2,000 men and are composed of cavalry (Nobility), Gallowglass, kearn and a small body of English soldiers who have deserted to him to provide modern weapon skills to his host. O’Donnell’s initial force is only about 40-foot and 80 horse (his personal guard).

O’Donnell’s horsemen harass O’Neill’s men immediately after his fording of the river, leaving O’Donnell a short breathing space to locate his small force in a more defensible position, at Magherennan (near today’s entrance to the Letterkenny Rugby club). When their lord is in position the O’Donnell cavalry withdraws and there O’Donnell awaits his reinforcements. While his opponent waits, O’Neill sets up his camp in Cluain Aire beside the river to cover the ford. When O’Donnell’s troops finally arrive, they number 400 Gallowglass from all the MacSweeney septs. With this virtual parity in the usually decisive heavy infantry, the O’Donnell host proceeds to advance on O’Neill’s camp. When first perceiving their attack, Shane says, “It is very wonderful and amazing to me that those people should not find it easier to make full concessions to us, and submit to our awards, than thus come forward to us to be immediately slaughtered and destroyed.”

This statement, made just as the armies meet, is possibly a late attempt to put heart into his own surprised army. Significantly, the main O’Donnell war host has employed rising ground to successfully cover their advance until it is far too late for O’Neill to deploy his own Gallowglass spars into proper line of battle to hold the enemy while the O’Neill horse mount up. The O’Neill army are caught utterly unprepared, in much the same way as O’Neill himself had taken a MacDonnell host by surprise at Glentaisie in 1565. Despite the element of surprise and O’Neill’s lack of manoeuvre room, the resistance of the surprised O’Neill Gallowglass in this encounter battle is at first successful for the Four Masters state that the action lasted “for a long time.” Eventually, with their loose protective screen of Gallowglass cut down, a panicked rout of Shane’s force ensues. The O’Donnell pressure of attack continues so fiercely that the broken O’Neill host is forced back on the ford and attempts to recross the Swilly. As the tide is now coming in, many of them drown in the speeding rush of waters. O’Neill’s losses are estimated by their enemies at 1,400 men killed and no prisoners are mentioned, although the English sources note a more credible total of 680 dead. With many of his most senior commanders and advisors killed amid the chaos of the first onslaught, O’Neill himself escapes the final slaughter with the timely aid of a party of the Gallaghers. They guide him to Ath an Tairsi (Ford of protection), near Crieve Smith in Oldtown today, where they escort him to his own territory and relative safety.

Many of the Donnelleys, Shane’s foster family and the source of his strongest support, defend him to the last and are decimated at Farsetmore. Abandoned by his tanisté and all of his Urríthe, literally under-kings, and with the destruction of his army, the “most powerful force Gaelic Ireland had yet witnessed,” Shane begins looking for a mercenary force to sustain him until he can make good his losses. With all other options closed, he turns to a warband hired to fight against him the previous winter by William Piers from among the MacDonald’s of Dunnyveg. He arrives at their camp at Cushendun with a small retinue and during their negotiations an altercation occurs, in which Shane is killed. Despite being engineered by Piers, this assassination has gone down in history as retribution for Shane’s military action against the MacDonalds in 1565. Shane is buried in a place called CrossSkern Church at Ballyterrim townland in the hills above Cushendun. Later his remains are exhumed with his head then being sent to Dublin.

(Pictured: An artist’s impression of an O’Donnell gallowglass dispatching an O’Neill kern in the waters of the Swilly, with Glebe Hill in the background, May 8, 1567)