Fulk V of Anjou Switches Sides: A Turning Point for Henry I (May 1119 CE)

By May 1119, King Henry I of England successfully turned the tide of the war in Normandy by enticing Fulk V of Anjou to abandon the Capetian alliance and support the Anglo-Norman cause. This diplomatic maneuver significantly weakened the anti-Norman coalition, allowing Henry to consolidate his hold over Maine and focus on crushing his remaining enemies.

The Betrothal of William Adelin and Matilda of Anjou

• To secure Fulk's loyalty, Henry finally agreed to the long-negotiated betrothal of his son and heir, William Adelin, to Fulk’s daughter, Matilda.
• In addition to the marriage alliance, Henry paid Fulk a large sum of money, effectively buying Anjou’s neutrality.
• With this agreement, Fulk V abandoned his support for King Louis VI of France and ceased hostilities with Henry, weakening the Capetian side of the war.

Fulk Departs for the Levant, Leaving Maine Under Henry’s Control

• Following the agreement, Fulk left for the Levant, where he would eventually become King of Jerusalem (1131).
• With Fulk’s departure, the County of Maine fell into Henry’s hands, further solidifying Anglo-Norman control over the region.

Strategic Consequences

• Henry no longer faced threats from Anjou, allowing him to redirect his military efforts against the remaining rebel barons and Capetian-backed forces.
• With Maine under his control, Henry strengthened the Norman frontier, creating a buffer zone against future incursions from France.
• The anti-Norman alliance began to fracture, shifting momentum in Henry’s favor and paving the way for his decisive victory at Brémule later in 1119.

The Anglo-Angevin marriage alliance between William Adelin and Matilda was a crucial political victory for Henry I, securing Normandy’s stability and eliminating one of his most dangerous rivals in the ongoing war with Louis VI of France.