The Skaggs-Files

Geoffrey V (August 24, 1113 - September 7, 1151), Count of Anjou and Maine, and later Duke of Normandy, called "Geoffrey the Fair" or "Geoffrey Plantagent", was the son of Fulk V, Count of Anjou and King of Jerusalem. Geoffrey's mother was Eremburg of La Fleche, heiress of Maine. Geoffrey himself became the father of the Plantagenet dynasty of English kings.

Nicknamed for the sprig of broom (= ''gen t'' plant, in French) he wore in his hat as a badge, at the age of 15 he married Matilda, the daughter of Henry I of England and widow of Henry IV, Holy Roman Emperor. The marriage in 1128 was meant to seal a peace between England/Normandy and Anjou. She was eleven years older than Geoffrey, and their marriage was a stormy one, but she survived him. Their eldest son became Henry II of England.

The year after the marriage Geoffrey's father left for Jerusalem (where he was to become king), leaving Geoffrey behind as count as Anjou.

When King Henry died in 1135, Maud's cousin Stephen seized the throne. While Maud turned her attentions to England, Geoffrey focused on the conquest of Normandy. This was to take a decade of steady seigework and alliance-building, a process Geoffrey would not abandon even when his wife pleaded for help in England. The merits of this strategy are sometimes debated. While Angevin forces might have been decisive if brought over to England, it also seems that the possession of Normandy played a role, possibly even a decisive one, in the eventual success of their son Henry in taking the English crown.

Geoffrey also put down three baronial rebellions in Anjou, in 1129, 1135, and 1145-1151. The threat of rebellion slowed his progress in Normandy, and is one reason he could not intervene in England.

In the remaining years of his life, Geoffrey consolidated his hold on Normandy, reforming the administration of the duchy, and, in 1150, introduced Henry into its rule.

He died on September 7, 1151, still a young man, and is buried in Le Mans Cathedral in France.

Geoffrey and Matilda had three sons, Henry, Geoffrey, and William. He also had an illegitimate son, Hamelin de Warenne.

The first reference to Norman heraldry was in 1128, when Henry I of England knighted his son-in-law Geoffrey and granted him a badge of gold lions (or leopards) on a blue background. (A gold lion may already have been Henry s own badge.) Henry II used two gold lions and two lions on a red background are still part of the arms of Normandy. Henry's son, Richard I, added a third lion to distinguish the arms of England.
References
Jim Bradbury, "Geoffrey V of Anjou, Count and Knight", in The Ideals and Practice of Medieval Knighthood III
Charles H. Haskins, "Normandy Under Geoffrey Plantagenet", The English Historical Review, volume 27 (July 1912), pp. 417-444