Domnall Gerrlámhach

Domnall Gerrlámhach
King of Dublin
Domnall's name as it appears on folio 48r of Oxford Bodleian Library MS Rawlinson B 489 (the Annals of Ulster).
Died	1135 Lismore
House	Uí Briain
Father	Muirchertach Ua Briain
Mother	Derb Forgaill ingen Uí Laidcnén

Domnall Gerrlámhach (died 1135), also known as Domnall Gerrlámhach Ua Briain, Domnall mac Muirchertaig, and Domnall Ua Briain, was an obscure twelfth-century Uí Briain dynast and King of Dublin. He was one of two sons of Muirchertach Ua Briain, High King of Ireland. Domnall's father appears to have installed him as King of Dublin in the late eleventh- or early twelfth century, which suggests that he was his father's successor-designate. Although Domnall won a remarkable victory in the defence of the Kingdom of Dublin in the face of an invasion from the Kingdom of Leinster in 1115, he failed to achieve the successes of his father. After his final expulsion from Dublin at hands of Toirdelbach Ua Conchobair, King of Connacht, and the death of his father, Domnall disappears from record until his own death in 1135. He was perhaps survived by two sons.

Domnall was one of two recorded sons of Muirchertach Ua Briain, High King of Ireland (died 1119); the other being Mathgamain (died 1129). Domnall was a member of the Uí Briain, a branch of the Dál Cais, descended from the eponymous Brian Bóruma mac Cennétig, High King of Ireland (died 1014). Domnall's mother was Derb Forgaill, daughter of Lethlobar Ua Laidcnén, King of Airgíalla. The fourteenth-century Annals of Tigernach accord Domnall the epithet gerrlámhach ("short-armed") which may indicate—if the term is taken literally—that he suffered some sort of deformity.

Muirchertach Ua Briain was one of three sons of Toirdelbach Ua Briain, High King of Ireland (died 1086), a man who secured control of the Kingdom of Munster in the 1060s before gaining the high-kingship of Ireland less than a decade later. In 1175, in an act of overlordship over the Kingdom of Dublin, Toirdelbach Ua Briain appointed Muirchertach Ua Briain King of Dublin, following a precedent set by Diarmait mac Maíl na mBó, King of Leinster (died 1072), a previous claimant to the Irish high-kingship who had done the same to his own eldest son, Murchad (died 1070), in 1052. When Toirdelbach Ua Briain finally died in 1086, his sons bitterly contested the kingship of Munster before Muirchertach Ua Briain succeeded in securing it for himself. By 1091, the latter appears to have regained control of the Dublin, only to lose it to Gofraid Crobán, King of the Isles (died 1095), who united it with the Kingdom of the Isles. Gofraid's reign in Ireland was short-lived, as Muirchertach Ua Briain forced him from Dublin in 1094. After the Gofraid's death the following year, Muirchertach Ua Briain appointed his own nephew, Domnall mac Taidc (died 1115), as King of the Isles. Uí Briain influence in the Isles was similarly short-lived, however, as Domnall mac Taidc was apparently forced from the region, and Magnús Óláfsson, King of Norway seized control of not only the Isles, but perhaps even Dublin itself, before falling in battle in 1103. Later in 1111, Domnall mac Taidc temporarily seized the kingship of the Isles in an act that may been opposed by his aforesaid uncle. The reasons for Domnall mac Taidc's exit from the Isles are uncertain. Although he may have been forcibly ejected by the Islesmen, he may well have returned to Ireland to take advantage of Muirchertach Ua Briain's rapidly failing health.