Mac William Íochtar

Mac William Íochtar (Lower Mac William), also known as the Mayo Burkes, were a partly Gaelicised branch of the Hiberno-Norman House of Burke in Ireland. The territory covered much of the northern part of the province of Connacht. The Mac William Íochtar functioned as a regional king and received the White Rod. The title was a successor office to the Lord of Connacht which ended upon the assassination of William Donn de Burgh, 3rd Earl of Ulster, in June 1333.

As a result of the Burke Civil War of the 1330s, the Lordship of Connacht was split between two opposing factions of the de Burgh family: the Burkes of Mac William Uachtar (or Clanricarde) in southern Connacht and the Mac William Íochtar Bourkes of northern Connacht. For over three hundred years, the two families dominated the politics of the province, frequently fighting each other for supreme rule of both the Anglo-Irish and Gaelic-Irish peoples.

In 1590-93 Tibbot ne Long accepted terms of surrender and regrant. In 1627 he was created Viscount Mayo.

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