Fulk IV of Anjou (1043 – 1109), also known as Fulk le Réchin, was count of Anjou from 1068 to 1109.

The nickname by which he is usually referred has no certain translation. Philologists have made numerous very different suggestions, including "quarreler", "sullen", and "heroic".

He was the younger son of Geoffrey (sometimes known as Alberic), count of Gâtinais, and Ermengarde of Anjou, a daughter of Fulk Nera, count of Anjou, and sister of Geoffrey Martel, also count of Anjou.

When Geoffrey Martel died without direct heirs he left Anjou to his nephew Geoffrey IV of Anjou, Fulk le Réchin's older brother.

Fulk fought with his brother, whose ruled was deemed incompetent, and captured him in 1067. Under pressure from the Church he released Geoffrey. The two brothers soon fell to fighting again, and the next year Geoffrey was again imprisoned by Fulk, this time for good.

Substantial territory was lost to Angevin control due to the difficulties resulting from Geoffrey's poor rule and the subsequent civil war. Saintonge was lost, and Fulk had to give the Gâtinais to Philip I of France to placate the king.

Much of Fulk's rule was devoted to regaining control over the Angevin baronage, and to a complex struggle with Normandy for influence in Maine and Brittany.

In 1096 Fulk wrote an incomplete history of Anjou and its rulers, though the authorship and authenticity of this work is disputed. If he did write it, it is one of the first medieval works of history written by a layman.

Fulk may have married as many as five times; there is some doubt regarding two of the marriages.

His first wife was Ermengarde de Beaugency. After her death he married Ermengarde de Borbon, and then possibly Ermengarde de Châtellailon. Both these were repudiated, possibly on grounds of consanguinity.

Next he married Bertrade de Montfort, who apparently left him for Philip I of France. Finally, he may have married a daughter of Walter of Brienne.

He had two sons. The eldest (a son of Ermengarde de Borbon), Geoffrey Martel II, ruled jointly with his father for some time, but died in 1106. The younger (a son of Bertrade de Montfort) succeeded as Fulk V.

He also had a daughter, Ermengarde, who married William VII the Young, count of Poitou and duke of Aquitaine.

References

Jim Bradbury, "Fulk le Réchin and the Origin of the Plantagenets", in Studies in Medieval History Presented to R. Allen Brown