Notes:

A descendant of Strongbow, he succeeded his older brother, Gilbert, in 1308 as Lord of Thomond. In 1309, and then again between 1312 and 1316, he was sheriff of Cork. Forced to put down a number of rebellions, he was eventually killed while commanding his forces at the Battle of Dysert O'Dea near what is now Ennis, County Clare. He was nominally succeeded by his son, Thomas, who was born in 1318 and died three years later; at that point the Anglo-Norman presence in Thomond disappeared.

The Battle of Dysert O'Dea took place on 10 May 1318 at Dysert O'Dea near Corofin, Ireland. It was part of the Bruce campaign in Ireland. The Norman Richard de Clare attacked the Gaelic Irish chieftain Conchobhar Ó Deághaidh, chief of the Cineal Fearmaic and ally of Muirchertach Ó Briain, but he was defeated.

Precursors to War

The Bruce invasion of Ireland enabled the outbreak of a number of small wars that had little, if anything, pertaining to the Scots. Perhaps the most notable was the battle at Dysert O'Dea which erupted in Brian Boru's old Kingdom of Thomond in 1318.

Two factions of the O'Brien clan had been fighting for generations for supremacy in Thomond. Murtough O'Brien, the descendant of Thurlough O'Brien was the rightful King of Thomond. A challenger appeared in the form of Mahon O'Brien, allied with the opposing faction of the family, which paid its homage to Brian O'Brien. This side of the family was allied with the powerful Anglo-Norman Richard de Clare, a descendant of Strongbow. De Clare ruled over much of western Ireland from his castle at Bunratty, yet the English respected Thomond as a sovereign state and remained outside its borders. However, de Clare's alliance with Mahon O'Brien provided an excuse to invade Thomond. His pale Englishmen would meet in a pitched battle against Murtough's Irish in the Battle of Dysert O'Dea near what is now Ennis, County Clare.

During this time, Donnchadh, an ally of de Clare, was overwhelmingly defeated in the Battle of Lough Raska near Corcomruadh Abbey.

Order of battle

When news arrived of his allies' defeat at Corcomruadh, Richard de Clare decided to attack the Gaelic stronghold at Dysert O'Dea. His troops arrived at Ruan on the morning of May 10, 1318, and were divided into three columns. The first division was headed by de Clare's son and marched northwards to Tullach O'Dea in an effort to cut off any help which might arrive from O'Connor of Ennistymon. The second column travelled southwards towards Magowna to quell any support from that direction. The third division was commanded by de Clare himself and marched westwards towards Dysert O'Dea, the home of Conor O'Dea. O'Dea intentionally made his forces look few in number, for some time fighting in retreat, and when de Clare charged for an attack the Anglo-Normans were ambushed. Richard de Clare was felled by an axe and his son was killed by a Feilim O'Connor. The O'Deas were reinforced by the O'Connors who were followed by the O'Briens, O'Hehir and MacNamaras and the English were soon defeated. Following their victory, the Irish marched back to the De Clare settlement, only to find that de Clare's wife had set it aflame, including Bunratty Castle, and had returned to England.

Over eighty Englishmen of noble birth and many foot soldiers were killed in the battle. The Kingdom of Thomond remained beyond foreign control for over two hundred years, until 1570.