 He was born in The Hague to the Dutch general Henry de Nassau d'Auverquerque (called "Lord Overkirk" by the English) and his wife Frances van Aerssen, and baptised there 30 May 1673.On 12 January 1697, he married his first cousin Lady Henrietta Butler, daughter of Thomas Butler, Earl of Ossory and sister of James Butler, Duke of Ormonde.In 1698, during his father's lifetime, he was created Baron Alford, Viscount Boston and Earl of Grantham by William III.