Counts · Duchy of Brittany · as at first light, 1 January 1200

Porhoët

The Porhoët, centred on Josselin on the Oust, the inland lordship whose head was briefly duke in the 1150s and fought Henry II in the 1160s and 1170s.

Now a quiet baronial house of central Brittany.

Who he is

Name
Eudo III of Porhoët (Eudes, Eon)
Title
Count (viscount) of Porhoët
Since
Not pinned: his father Eudo II, duke by marriage 1148-1156 and Henry II's enemy, died after 1180 (about 1185 in one genealogy)
Born
Not pinned (son of Eudo II, probably by his second wife Jeanne of Léon, married August 1167)
Family
Son of Eudo II of Porhoët; his wife's name is not known; dies 1231 (Medieval Lands; other genealogies give 1234 or 1239). His half-sister Adelaide is a former abbess of Fontevraud.
Confidence
medium

Medieval Lands and genealogies collected on acvancestors.com; his tenure in 1200 follows from his father's death after 1180.

Overlord

The duke of Brittany

What it holds

  • Josselin castle
  • La Trinité-Porhoët
  • Loudéac and La Chèze
  • Mauron and Merdrignac

How it was acquired

Hereditary.

Allies and rivals

Rohan to the west; Ploërmel (ducal) to the south; Fougères by marriage.

How things stand that morning

Holds Porhoët under the duke; quiet.

Wealth

Forest of Brocéliande edges, upland cattle.

Military

Castle of Josselin.

Places of note

  • Josselin: Seat

Where the sources disagree

Evidence: Holder identified from genealogies citing Medieval Lands; no act of 1199-1200 checked.

On the map: Approximate.

Primary sources for Brittany

Chronicles, registers, sagas and inscriptions written in or near 1200 that cover this entry. Each has its own page with editions, translations and where to read it.

  • Chronicles of the Churches of Anjou (Saint-Aubin, Saint-Serge, Saint-Florent and others), Various (monks of Angers and the Loire) (11th to 13th centuries; the Saint-Aubin annals run to the 1220s). The Angevin houses' own annals of the succession crisis in their city: Arthur received at Angers in 1199 with Constance and the Breton and Angevin barons, John's counter-moves, the defection of William des Roches and the Angevin lords to John, and the peace of 1200 that left Arthur John's vassal. Read online
  • The Great Chronicle of Tours, Anonymous (a canon of Saint-Martin of Tours) (about 1227). The Loire valley's view of the Angevin succession. Read online
  • History of the Dukes of Normandy and the Kings of England, Anonymous of Bethune (a clerk in the household of Robert VII of Bethune) (about 1220). A Flemish lord's clerk writing twenty years on, with a soldier's interest in who fought whom. Read online
  • The Acts of Philip Augustus, with Delisle's Calendar, Various (the French royal chancery) (1179 to 1223). The king's own charters and treaties for the year: the peace of Peronne with Baldwin IX in January 1200, the treaty of Le Goulet with John on 22 May 1200, the marriage settlement for Louis and Blanche, the privilege for the scholars of Paris, grants to towns, abbeys and Norman lords, and the first acts of the king's new acquisitions in the Vexin, Evreux and Berry. Read online

Sources and studies

  1. Medieval Lands: Brittany
  2. Eudo II of Porhoët and family (acvancestors.com, citing Medieval Lands and Wikipedia)

Last revised 4 November 2026. Published 4 November 2026. Suggest a correction on the OMNIA Discord.