• Born: Abt 1056, Hainault, Belgium
• Married: 1084
• Died: 1098, after 8 June, near Nikaia, Illyria, on Crusade

  Research Notes:

Guibert describes him as "Balduinus comes de Montibus, Roberti Flandrensis comitis iunioris patrui, filius". "Balduino frater eius [Arnulphum occiso]" is named in the Cartulaire de Saint-Bertin.

He succeeded his brother in 1071 as BAUDOUIN II Comte de Hainaut et de Valenciennes. By agreement at Liège in 1071, procured by Emperor Heinrich IV King of Germany with the aim of confirming the status of the counties of Hainaut and Valenciennes as imperial fiefs, Baudouin's mother (on his behalf) surrendered the two counties to the emperor, who granted them to the bishop of Liège. The bishop then granted the counties to Godefroi III "le Bossu" Duke of Lower Lotharingia, who in turn granted them back to Baudouin and his mother. This process also ensured imperial protection for Hainaut as well as comte Baudouin III's succession, which no doubt would otherwise have been threatened by his uncle Robert I Count of Flanders. "Balduinus, Valenciarum comes, filius Balduini junioris" confirmed the purchase by the abbot of Hasnon of two mills, for the souls of "patris mei Balduini et matris mee Ricildis", by charter dated 1087. Comte Baudouin joined the contingent of Godefroi de Bouillon Duke of Lower Lotharingia (avoiding that of Robert I Count of Flanders) on the First Crusade in 1096, selling the castle of Couvin to Otbert Bishop of Liège to raise funds. Otbert Bishop of Liège declared having bought "castellum de Covino" from "comite Balduino de Mont", in the presence of "uxore ipsius Ida, cum filiis suis Baldewino, Arnulpho, Lodewico, Heinrico", by charter dated 14 Jun 1096, signed by "Rainerus advocatus, comes Warnerus de Greis, Wedericus de Walecourth…". William of Tyre names "Baudoin comte de Hainaut" among those who left on the First Crusade with Robert Count of Flanders.Albert of Aix records that "Hugonem Magnum fratrem regis Franciæ, Drogonem et Clareboldum" were held in chains in prison by the emperor at Constantinople but were released after the intervention of "Baldewinus Hainaucorum comes et Heinricus de Ascha" who were sent as envoys by Godefroi de Bouillon. Albert of Aix names "…Baldewinus de Monte castello, Hainaucorum comes et princeps…" among those who took part in the siege of Nikaia, dated to mid-1097 from the context. He took part in the siege of Antioch in 1098. ²