John was the eldest son of Duke
John I of Brittany and
Blanche of Navarre. On 22 January 1260, he married
Beatrice, a daughter of King
Henry III of England. John was very close to his brother-in-law,
Edward I. In 1271, he accompanied Edward to the
Ninth Crusade, meeting there with his father and King
Louis IX of France. Louis succumbed to an illness in Tunis, and John's father returned to Brittany. John, however, followed Edward to Palestine. The crusade ended the following year, having achieved little. In 1285, John took part in the
Aragonese Crusade at the side of King
Philip III of France. Upon the death of his father on 8 October 1286, John succeeded him as duke of Brittany, inheriting also the
Earldom of Richmond in the
Peerage of England. His namesake son was governing
Aquitaine in the name of his uncle
EdwardI, when
King PhilipIV declared Edward's rule forfeit in May 1294 after Edward's refusal to stand before the
Parlement of Paris over fishing disputes the previous year that had escalated into naval warfare between the two countries. John assisted his brother-in-law in the ensuing
Gascon War but suffered only defeats. When the English army sought to recover by plundering the Breton
Abbaye Saint-Mathieu de Fine-Terre in 1296, however, John abandoned Edward's cause. In response, Edward deprived him of the earldom. John proceeded to ally himself with the French, arranging a marriage between his grandson
John and King Philip's cousin Isabella of Valois. Philip then raised him into the
Peerage of France in September 1297. During the negotiations over the final
Treaty of Paris ending the war, John was among Philip's chief negotiators with the English. From 1294 until 1304, John assisted the King of France in his campaign against
Count Guy of Flanders, taking part in the decisive
Battle of Mons-en-Pévèle. Following King Philip's victory, in 1305, John travelled to
Lyon to attend the
coronation of
Pope Clement V. John was leading the Pope's horse through the crowd during the celebrations. So many spectators had piled atop the walls that one of them crumbled and collapsed on top of the Duke. He died four days later, on 18 November. His body was placed in a lead coffin and sent down the
Loire. He was buried on 16 December in the
Carmelite convent he had founded in
Ploërmel. == Issue ==