Brian Bóruma mac Cennétig (941 – 23 April 1014) (known as Brian Boru in English) was High King of Ireland from 1002 to 1014. He was born in 941 near Killaloe. His father was Cennétig mac Lorcáin, King of Thomond and his mother was Bé Binn ingen Murchada, daughter of the King of West Connacht. He subsequently united the warring Irish Tribes to expel Danish vikings at the battle of Clontarf.

He belonged to the Dál Cais who occupied a territory straddling the River Shannon, known as the Kingdom of Thomond. The river served as an easy route by which raids could be made against Connacht and Meath. Both Brian's father and his older brother Mathgamain conducted river-borne raids, in which the young Brian participated and these became the root of Brian's appreciation for naval forces in his later career.

He developed a military strategy that coordinated use of forces on both land and water. Brian's naval forces, which included contingents supplied by the Hiberno-Norse cities that he brought under his control, provided both indirect and direct support for his forces on land. Indirect support involved a fleet making a diversionary attack on an enemy in a location far away from where King Brian planned to strike with his army. Direct support involved naval forces acting as one arm in a strategic pincer, the army forming the other arm.