Erispoë

Erispoe (French: Erispoë; Latin: Herispoius, Herispogius, or Respogius; d. 2 or 12 November 857) was Duke of Brittany from 851. After the death of his father Nominoe, he led a successful military campaign against the Franks, culminating in his victory at the Battle of Jengland. He is subsequently referred to as "King of Brittany".

Erispoe's recorded titles include provinciæ Brittaniæ princeps ("prince of the province of Brittany"), dux Brittonum ("duke of the Bretons"), and rex tyrannicus Brittonum ("usurping king of the Bretons"). However, if Erispoe was usurping regality in Brittany at that time (857), it is not attested in other sources. It may imply continued Frankish resentment of the title. He is called rex Brittonum ("king of the Bretons") by Regino of Prüm (d. 915).

Erispoe was born to Nominoe's wife Argentaela, but the date of his birth is not known. He was involved in his father's campaigns to take control of the Frankish counties of Rennes and Nantes. In 843, in alliance with Lambert II of Nantes, Erispoe took command of the Breton army while his father was ill. Lambert had been displaced as ruler of Nantes by Charles the Bald, king of West Francia, who had installed Renaud d'Herbauges in his place. Ambushed by Count Renaud, Erispoe was badly defeated at the initial engagement at Messac. However, the Brittons quickly rallied their troops and took the complacent Franks by surprise shortly thereafter at the Battle of Blain, inflicting a serious defeat resulting in the death of Count Renaud.

Having regained his health, Nominoe took command once more. The victory at Blain having secured control of Nantes and Rennes, he raided into Frankish territory, defeating the Franks at the Battle of Ballon in 845. A truce followed, but after Charles regained control of Nantes, Nominoe and Erispoe renewed their offensive in 849. While on campaign, Nominoe died suddenly. Erispoe was proclaimed leader, but immediately after his father's death, his power was challenged by Charles the Bald, still his nominal suzerain. Charles crossed the river Vilaine with an army. Erispoe defeated Charles in the decisive Battle of Jengland on 22 August 851.

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