L'homme armé
Most 15th-century masses were based on a cantus firmus, usually from a Gregorian chant, and most commonly put in the tenor voice. The cantus firmus sometimes appeared simultaneously in other voices, using a variety of contrapuntal techniques. Later in the century, composers such as Guillaume Dufay, Johannes Ockeghem, and Jacob Obrecht, used secular tunes for cantus firmi. This practice was accepted with little controversy until prohibited by the Council of Trent in 1562. In particular, the song "L'homme armé" has a long history with composers; more than 40 separate mass settings exist.