Geoffrey and Matilda's marriage led, through their son Henry II, to the 300-year long reign of the Plantagenet dynasty in England.

The chronicler John of Marmoutier described Geoffrey as handsome, red haired, jovial, and a great warrior.

Consent was obtained from both parties, and on 10 June 1128 the fifteen-year-old Geoffrey was knighted in Rouen by King Henry, who was also the duke of Normandy, in preparation for the wedding.

She was eleven years older than Geoffrey, and very proud of her status as dowager empress (as opposed to being a mere countess), and which she kept for the remainder of her life.

When his father in law, King Henry I of England, died in 1135, Geoffrey supported Matilda in entering Normandy to claim her inheritance.

The border districts submitted to her, but in England her first cousin Stephen of Blois had been crowned king, supported by a number of barons after claims that Henry I had changed his mind on his deathbed in regard to his heir.

[7] Geoffrey held the duchy until 1149, when he and Matilda conjointly ceded it to their son, Henry, which cession was formally ratified by King Louis VII of France the following year.

In 1153, the Treaty of Wallingford stipulated that Stephen should remain King of England for life and that Henry, the son of Geoffrey and Matilda should succeed him, beginning the Plantagenet era in English history.

Jean de Marmentier, a late-12th-century chronicler, reported that in 1128 Henry I of England knighted his son-in-law Geoffrey and granted him a badge of gold lions.