His father, Reginar III, was exiled in 958 as a rebel by Otto I, Holy Roman Emperor.
Hainaut was held after then by Godfrey I, Duke of Lower Lorraine, but Reginar IV claimed that Mons in Hainaut had been his father's.
He managed to replace Godfrey as Count of Mons in 998.
Regnier IV married Hedwig, daughter of Hugh Capet and Adelaide of Poitou.
[2] They had: This biographical article of a European noble is a stub.