Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
NASSAU
As described in historical dictionaries
Patronymica Britannica (1860)
NASSAU. William Henry, sou of Frederick de Nassau, natural son of Henry Frederick de Nassau, Prince of Orange, grandfather of King William III., accompanied the last-named personage to England in 1688, and was afterwards advanced to the peerage, as Earl of Eochford. Another Henry de Nassau also accompanied William III., and his son was created Earl of Grantham.