Herleva, the daughter of a tanner from Falaise in Normandy, was born in 1010. When she was sixteen gave birth to a son called Richard. The boy's father was Gilbert, Count of Brionne, one of the most powerful landowners in Normandy. As Herleva was not married to Gilbert, the boy became known as Richard Fitz Gilbert. The term 'Fitz' was used to show that Richard was the illegitimate son of Gilbert.
The following year, Herleva became the mistress of Robert, Duke of Normandy. In 1028, Herleva and Robert had a son who eventually became known as William, Duke of Normandy. Instead of marrying Herleva, Robert persuaded her to marry his friend, Herluin of Conteville. After marriage, Herleva had three more children, Odo, Robert and Muriel. Later the sons became known as Odo of Bayeux and Robert of Mortain.
In 1035, Robert, Duke of Normandy died. Although William was illegitimate, he was Robert's only living son, and so inherited his father's title. Gilbert, Count of Brionne, became William's guardian. A number of Norman barons would not accept an illegitimate son as their leader and in 1040 an attempt was made to kill William. The plot failed but they did manage to kill Gilbert of Brionne.
Gilbert of Brionne's large estates in Normandy were now passed on to his legitimate son, Baldwin of Flanders. As Richard Fitz Gilbert was illegitimate, he did not receive very much land when his father died. When William, Duke of Normandy, decided to invade England in 1066, he invited his three half-brothers, Richard Fitz Gilbert, Odo of Bayeux and Robert of Mortain to join him. Richard, who had married Rohese, daughter of Walter Giffard of Normandy, also brought with him members of his wife's family.
(S1) Geoffrey Malaterra, Chronicle (c. 1090)
The Normans are a most cunning and revengeful race. They leave their native fields for the hope of rich booty; greedy of gain. The Normans can flatter when they choose. The Norman leaders are most generous when they hope to earn fame by their generosity.
(S2) John Simkin, Herleva of Falaise (1996)
Herleva was the daughter of Fulbert, a tanner in Falaise. Robert, Duke of Normandy fell in love with this beautiful girl. Soon after their first meeting, Robert sent a message to Herleva asking her to meet him at his castle at Brionne. Within a year a little boy was born. He was given the name William. Many years later, the citizens in a town besieged by William made fun of him by hanging out animal skins over the city walls.