"L'homme armé" is a secular song from the Late Middle Ages, of the Burgundian School. According to Allan W. Atlas, "the tune circulated in both the Mixolydian mode and Dorian mode ." It was the most popular tune used for musical settings of the Ordinary of the Mass: over 40 separate compositions entitled Missa L'homme armé survive from the period.
"L'homme armé" in the Mellon Chansonnier, c. 1470
Missa "L'homme armé" for 12 voices (attributed to Giacomo Carissimi)
The Burgundian School was a group of composers active in the 15th century in what is now northern and eastern France, Belgium, and the Netherlands, centered on the court of the Dukes of Burgundy. The school inaugurated the music of Burgundy.
Composer Guillaume Dufay (left) and Gilles Binchois (right), Martin le Franc, "Champion des Dames"