The Battle of Farsetmore was fought near Letterkenny in Donegal, north-western Ireland, on the 8th of May 1567, between the O’Neill and O’Donnell clans. Shane O'Neill, chief of the O’Neills of Tyrone, was defeated and the O’Donnells freed themselves from O’Neill overlordship. Letterkenny (Leitir Ceanainn in Irish) is the largest town in County Donegal, in the Republic of Ireland, located 35 miles north of Donegal Town and 20 miles west of Derry in Northern Ireland. ... Donegal (Dún na nGall in Irish) is a town in County Donegal, Ireland. ... Shane ONeill (c. ... This article is about County Tyrone. ...

Background

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 in Antrim and O’Donnells in Donegal. In 1566, the English Lord Deputy of Ireland, Henry Sidney, gave military support to the O’Donnells against O’Neill, who was regarded as a destabilising and anti-English power in the north of Ireland. O’Neill forced out these English troops, but the new O’Donnell chieftain, Hugh O’Donnell, took the opportunity to assert his independence and raided O’Neill’s lands at Strabane. In response, O’Neill mustered his armed forces and marched into O’Donnell territory. Antrim in Northern Ireland may refer to Antrim town. ... Official standard of the Lord Lieutenant of Ireland The Lord Lieutenant of Ireland (also known as the Viceroy or in the Middle Ages as the Lord Deputy) was the head of Englands (pre-1707) or Britains (post 1707) administration in Ireland. ... Sir Henry Sidney (1529 - May 5, 1586), lord deputy of Ireland, was the eldest son of Sir William Sidney, a prominent politician and courtier in the reigns of Henry VIII and Edward VI, from both of whom he received extensive grants of land, including the manor of Penshurst in Kent...

The Battle

O’Neill crossed into Tir Connell (O’Donnell territory) by crossing the River Swilly about a mile north of Letterkenny. O’Donnell attacked him at a place called Farsetmore. Both sides are estimated at about 2000 men and were composed of similar troops, gallowglass mercenaries and clan levies. Lough Swilly (Loch Súilí in Irish) in Ireland is a fjord-like body of water lying between the eastern side of the Inishowen Peninsula in County Donegal and the rest of northern Donegal. ... Gallowglass (From Irish: gall-óglach meaning foreign warrior) were a type of Gaelic Irish warrior typical from about the 13th Century until the English Occupation in the 17th Century. ...

O’Donnell’s horsemen harassed O’Neill as his men were fording the river. Then, the two sides fought hand to hand combat. The O’Donnell horse got the better of O’Neill’s cavalry, precipitating a general retreat on behalf of O’Neill’s force. The O’Donnells pursued them back over the river Swilly– causing many of them to drown.

O’Neill lost between 600 and 1300 men killed. Looking for fresh troops, he turned to the MacDonnells of Antrim for an alliance. However, they had him murdered and sent his head to the English authorities in Dublin.

Sources

• G.A. Hayes McCoy, Irish Battles, Belfast 1989.