Dufay stayed in Cambrai during the 1440s. At the same time he was also in the service of the Duke of Burgundy. While in Cambrai he worked with Nicolas Grenon on completely renewing the cathedral collection of music. This meant that he had to write a big collection of polyphonic music for services. He also worked in the administration of the cathedral. In 1444 his mother died, and was buried in the cathedral; and in 1445 Dufay moved into the house of the person who had been canon just before. He kept this home for the rest of his life, although he did spend six more years in Italy where he wrote many of his compositions. When he returned again to Cambrai he was made canon of the cathedral. He was the most famous composer in Europe by that time. He often composed music for the court of Burgundy, and he met many younger composers who were becoming famous, such as Busnois, Ockeghem, Tinctoris, and Loyset Compère. During this period Dufay probably wrote his mass based on the song "L'homme armé", as well as the chanson based on the same song. Maybe he wrote this when Philip the Good called for a new crusade against the Turks, who had recently captured Constantinople. He also wrote a Requiem mass around 1460, which is lost.