Given the almost complete elimination of 15th century music manuscripts in England, largely by Henry VIII during the Dissolution of the Monasteries in the 1530s, it is not surprising that most of Morton's music survives in sources from the Continent, and if he was ever active as a musician in his native land, all trace is lost. Eight pieces survive, all rondeaux. One of the most famous of them is the earliest known setting of the tune l'homme armé, which was used by many early Renaissance composers as a cantus firmus for the Mass. This piece, a quodlibet, is probably datable to May 1464; it seems to have been written as a departure gift for another court composer, Simon le Breton.