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John I
duke of Brittany
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Also known as: Jean le Roux, John the Redhead
John I (born 1217—died 1286) was the duke of Brittany (from 1237), son of Peter I. Like his father, he sought to limit the temporal power of the clergy; consequently he was excommunicated, upon which he journeyed to Rome to win absolution. Subsequently, he and his wife, Blanche of Champagne, traveled with St. Louis on the crusade to Tunisia (1270).