Medardus was one of the most honored bishops of his time, often depicted laughing, with his mouth wide open, and therefore he was invoked against toothache.

[3] A pious fiction links his childhood to his future bishoprics: "He often accompanied his father on business to Vermand and Tornacum (modern Tournai), where he frequented the schools, carefully avoiding all worldly dissipation".

During 481–511, the Salian Frankish king Clovis I conquered and united several Germanic successor states to form the Kingdom of Francia, the predecessor of modern France and Germany.

His piety and knowledge, considerable for that time, caused Bishop Alomer of Vermand to confer on him Holy Orders.

[4] He is held to have removed the seat of his bishopric from Vermand, a little city with no defences, to Noviomagus Veromanduorum (modern Noyon), the strongest place in that region of Neustria, in 531.

[2] That year Clotaire marched against the Thuringii with his brother Theuderic I, but struggles with the Burgundians also troubled Merovingian Neustria.

It is also claimed that in 532, at the death of Eleutherius, bishop of Tornacum, Medardus was invited to assume the direction of that diocese also.

King Clotaire, who had paid Medardus a last visit at Noviomagus, where the bishop died, had his body transferred to his own manor of Croviacum (modern Crouy),[5] at the gates of the royal city of Noviodunum; there over his tomb was erected the celebrated Benedictine abbey which bears his name, the Abbey of Saint-Médard.

The selection of the site was given authenticity through a familiar trope of hagiography: Medardus was one of the most honored bishops of his time.

His memory has always been popularly venerated, first in the north of France, then in Cologne and extending to western Germany,[6] and he became the hero of numerous legends.