Deffès was born in Toulouse and admitted to the Paris Conservatory in 1839, where he studied with Fromental Halévy and Henri Montan Berton (composition), François Bazin (harmony), Auguste Barbereau (counterpoint and fugue), and Théodore Mozin (piano).

The piece gained great popularity and became a signature tune of his home town.

During his stay in Rome, which was connected with the prize, he composed his Messe solennelle, which was first performed in 1850.

Instead, he now wrote compositions such as the Marche funèbre, the motet Gaude floris, a Messe brève à trois voix and the song La Phrygienne for choir and piano.

His symphonic overture Un Triomphe à Rome was performed at the 1878 World Exhibition.