Born in
Valenciennes, he was probably the son of a
castellan of the town mentioned in 1141. He seems to appear in the official record in 1180. After the accession of
Baldwin IX as
Count of Flanders in 1194 he appears on several important acts of Baldwin, including the treaty between the latter and
Richard Lionheart in June/July 1197 and another in 1199 with
John Lackland. He took the cross alongside his suzerain; in the spring 1203, in Corfu, he was one of the few leaders who advocated in favor of the diversion of the
Fourth Crusade to
Constantinople. After the
conquest of Constantinople and the establishment of the
Latin Empire, Renier was granted
Philippopolis and the territory as far as the river
Maritsa by
Emperor Baldwin I following the October 1204
partition of the conquered and yet to be conquered lands of the
Byzantine Empire. Renier's land lay within the realm of
Bulgaria, in territory claimed by Byzantium and subsequently the Franks. Renier's first campaigns that fall and winter to take possession of his imperial fief were successful, but the next year Bulgarian
tsar Kaloyan swooped down and took
Adrianople and threatened Philippopolis. Renier was abandoned by his son Renier, his brother Gilles, his nephew James of Bondues and his son-in-law Achard of Verli, which tried to go to Constantinople but were captured and executed by Kaloyan. With only a small force remaining at his command, Renier holed up in the castle of
Stenimaka. It was during an effort to relieve Adrianople that Emperor Baldwin was captured. In the summer of 1205, the
Paulicians of Philippopolis tried to surrender the city to Kaloyan, but Renier sallied from his fortress and razed their quarter of the city, leaving the rest to the brave defence of the united Latin and Greek populations, who declared
Alexios Aspietes as emperor. Nevertheless, the city was taken and the Greek quarter burned. Later that same year, the imperial regent
Henry of Flanders marched into Bulgaria and relieved Stenimaka and Renier in July 1206. == References ==