 His mother was Lady Honora Burke (1675–1698), second daughter of William Burke, (d. 1687), the seventh Earl of Clanricarde and widow of the Irish Jacobite nobleman Patrick Sarsfield, 1st Earl of Lucan.Sarsfield and Berwick were both veterans of James II's Irish Army and went into continental exile as part of the Flight of the Wild Geese.Unfortunately, his mother died young at Pezenas, in the Languedoc, South of France, on the 16 January 1698, when he was less than 18 months old.