Willem was a lay brother in the Cistercianabbey of Ter Doest in Lissewege. During the Battle of the Golden Spurs in 1302 he unhorsed the French leader, Count Robert of Artois, who was then killed by other Flemish fighters. This episode in the battle was represented in a painting by Nicaise de Keyser, displayed in Kortrijk, which was destroyed in the bombing of 21 July 1944, when around 300 Avro Lancasters dropped over 5,000 bombs on the city center.[1] A preliminary study can still be seen in the Stedelijk Museum in Kortrijk. During the battle, he killed many French knights.[further explanation needed] Contemporary chroniclers[who?] stress that he was a very large and extraordinarily strong man. He rode to the battlefield and then exchanged his mount for a goedendag and a spear or sword.
During a revolt of the lay brothers of Ter Doest Abbey in November 1308, he killed the elderly cellarer and severely injured the abbot, Willem van Cordewaeghen. Willem van Saeftinghe sought sanctuary in the church of Lissewege. When the news reached Bruges, Jan Breydel and a son of Pieter de Coninck with 80 inhabitants of the city marched to free him, and carried him back in triumph to Bruges, to the great displeasure of the count, the burghers and the nobility of Flanders.
