Herleva

Eventually Robert gave in, and the brothers clasped hands, made peace, and parted on good terms.

Robert's partner, a woman named Herleva, was from Falaise, and their son William was born there, probably in 1027 or 1028.

So the future conqueror was born in the very town his father had held against his own brother, something that later chroniclers found poetic.

Richard, meanwhile, had other business, and a charter from January 1027 shows him granting a marriage settlement to a bride named Adela.

The king who we know as William I of England, AKA William the Conqueror, born on or about the 8th of November 1028 in Falaise, which is in northeast France, in what was then the Duchy of Normandy.

His parents were Duke Robert I of Normandy and Herleva.

They were unmarried, hence William was known as William the Bastard then and still.

Given that it was a duchy, not a kingdom in Normandy, his illegitimacy wasn't a barrier to him succeeding to the duchy, which he did very early in life.