Louis de Citeaux was a 13th century Frenchman. His brother was the Bishop of Citeaux.
He hired his soldiers out as mercenaries to Francisco Guzman, knowing he was trying to gain the Papacy. Should Guzman have succeeded, de Citeaux would have increased his influence. His soldiers killed Guzman's main rival, Chretien d'Alsace.
Later, Guzman decided that de Citeaux was dangerous to him since he could reveal his involvement in d'Alsace's death, so Guzman had him killed. (PROSE: Sanctuary)