The O’Neills, as one of the most powerful Gaelic dynasties in Ireland, were constantly involved in warfare: against rival Irish clans, the Anglo-Normans, and later the Tudor/Elizabethan English crown. Below is an outline of their key battles
Clontibret (1595) – O’Neill victory.
Yellow Ford (1598) – O’Neill’s greatest triumph.
Curlew Pass (1599) – Allied victory (O’Donnell with O’Neill support).
Moyry Pass (1600) – Indecisive, heavy English losses.
Kinsale (1601) – Decisive O’Neill defeat → collapse of Gaelic Ulster.
Medieval O’Neills (12th–15th centuries)
After the Norman invasion of Ireland (1169), the O’Neills became the principal defenders of Ulster:
Battle of Down (1260)
Brian O’Neill, King of Tír Eoghain, allied with other Irish lords against the Normans.
Defeated by John de Courcy’s successors and the Anglo-Normans.
Brian O’Neill was killed, a major setback for Gaelic Ulster.
Ongoing wars with the Earls of Ulster (Normans)
Throughout the 13th–14th centuries, the O’Neills fought the de Burgh Earls of Ulster.
Eventually, after the murder of the last Earl of Ulster in 1333, the O’Neills reasserted dominance in Ulster.
Tudor Era – The Great Struggle with England
The 16th century saw the O’Neills lead the last great stand of Gaelic Ireland against the expanding Tudor state:
Battles of Shane O’Neill (1550s–1567)
Shane the Proud fought both English forces and rival Gaelic clans.
His campaigns (including against the MacDonnells of Antrim and O’Donnells of Donegal) kept Tyrone largely independent until his death in 1567.
Nine Years’ War (1594–1603) – Hugh O’Neill, Earl of Tyrone
The greatest O’Neill war, fought between Hugh O’Neill (1550–1616) and Elizabeth I’s armies:
Battle of Clontibret (1595) – O’Neill victory.
Hugh O’Neill ambushed and defeated English forces under Sir Henry Bagenal in Monaghan.
Proved the O’Neills could match professional English troops.
Battle of the Yellow Ford (1598) – O’Neill’s greatest triumph
Hugh O’Neill’s greatest victory.
Crushed a large English army near Armagh, killing Sir Henry Bagenal.
Sparked widespread rebellion across Ireland.
Battle of Curlew Pass (1599) – (allied O’Donnell victory, but with O’Neill support)
Red Hugh O’Donnell (ally of O’Neill) destroyed an English force under Sir Conyers Clifford in Connacht.
Battle of Moyry Pass (1600)
Hugh O’Neill inflicted heavy losses on Lord Mountjoy’s army but ultimately had to withdraw.
Battle of Kinsale (1601)
Decisive battle of the war.
O’Neill and O’Donnell allied with a Spanish expeditionary force.
English forces under Lord Mountjoy and Charles Blount defeated the Irish-Spanish army.
This marked the turning point and led to the collapse of Gaelic resistance.
Aftermath – Collapse of Gaelic Power
1607 – The Flight of the Earls: Hugh O’Neill and Rory O’Donnell fled Ireland → end of Gaelic leadership in Ulster.
The Plantation of Ulster (1609) followed, permanently transforming Irish society.