John I of Brienne, Count of Eu


John I of Brienne was the son of Alphonso of Brienne and Marie de Lusigan. His mother was the heiress of Eu, Seine-Maritime, and he succeeded his father as Count of Eu in 1270.
He married Beatrice, the daughter of Guy III, Count of Saint-Pol. They had:
  1. John II of Brienne, Count of Eu
  2. Isabelle, married John II of Dampierre, Viscount of Troyes
  3. Jeanne, married first Raymond VI, Viscount of Turenne, married second before 4 August 1314 Renauld, Lord of Picquigny, vidame of Amiens
  4. Marguerite, married Guy, Viscount of Thouars
  5. Mahaut, married Alfonso de la Cerda
John died at Clermont-en-Beauvaisis in 1294.