This articleneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Guy of Thouars" – news ·newspapers ·books ·scholar ·JSTOR(August 2020) (Learn how and when to remove this message)

Guy of Thouars (died 13 April 1213) wasDuke of Brittany from 1199 to 1201 as the third husband ofConstance, Duchess of Brittany. They married inAngers,County of Anjou, between August and October 1199^[a][1] after her sonArthur entered Angers to be recognized as count of the three countships of Anjou, Maine and Touraine. He was an Occitan noble, a member of theHouse of Thouars.

Between 1196 and the time of her death in 1201, while delivering twin daughters, Constance ruled Brittany with her young son, Arthur I, as co-ruler. Duke Arthur was captured in 1202 by his uncleJohn, King of England, and disappeared in 1203. Arthur's elder full sisterEleanor, was captured along with him and imprisoned by John. Arthur was succeeded by his infant half-sister, Guy's daughterAlix of Thouars. Guy served as regent of Brittany for his daughter from 1203 to 1206.

In 1204, Guy as regent of Duchess Alix,vassal ofPhilip II of France, undertook the siege of theNorman island fortress ofMont Saint-Michel.^[2] Because the abbey would not surrender, he set fire to the village and massacred the population.^[b] The fire which he himself lit extended to the buildings, and the roofs were engulfed in flames. Philip II paid Abbot Jordan for the reconstruction cost.

In 1206 Philip II took the regency of Brittany himself, much to the consternation of the Breton nobles.^[c]

Guy died in 1213 inChemillé in the county of Maine, and was buried with Constance atVilleneuve Abbey, now in the commune ofLes Sorinières, outside ofNantes. 'Situated at Nantes south gate, Abbey de Villeneuve' was 'founded in 1201 by Constance de Panthièvre, the Duchess of Brittany ...'^[3]

Guy married Constance of Brittany in 1199.^[4] They had two or three^[5] daughters:

• Alix of Thouars, succeeded her half-brother in 1203 assuo jure Duchess of Brittany and Countess of Richmond;
• Catherine of Thouars, Dame ofAubigné; marriedAndrew III, Baron of Vitré^[6] in 1212;
• Margaret of Thouars.^{[d][7][8][9][e][10][11][12][13]}

Guy remarried Eustachie of Chemillé in 1203. They had two sons:

• Peter, Lord of Chemillé (1204-1254/55), who married Eleanor of Porhoët.
• Thomas of Chémillé (d. c. January 1246).

• Dukes of Brittany family tree
• Viscounts of Thouars

• Church, Stephen (2015).King John: And the Road to Magna Carta. Basic Books.
• Everard, J.A. & Jones, M.Charters of Duchess Constance of Brittany and her Family, The Boydell Press, 1999
• Everard, J.A.Brittany and the Angevins, Cambridge University Press, 2000

• 12th-century births
• 1213 deaths
• 12th-century dukes of Brittany
• 13th-century dukes of Brittany
• 13th-century regents
• Regents of Brittany
• Jure uxoris dukes
• Remarried jure uxoris officeholders

• Articles with short description
• Short description is different from Wikidata
• Articles needing additional references from August 2020
• All articles needing additional references
• Use dmy dates from March 2021
• Year of birth unknown