Medard (Latin Medardus) and his twin brother Gildard (Latin Gildardus) were — per the Frankish-Gallic Vita Medardi composed in the 7th century — born around 456 AD at the small Picard village of Salency to a Gallo-Roman Christian family. The brothers were raised together and ordained priest together; eventually they were consecrated bishops on the same day at different sees — Medard to the small Frankish diocese of Vermand (later transferred to Noyon, modern Picardy) around 530, Gildard to Rouen at the same date. The twin-brother bishop pair is a Frankish-Catholic hagiographic motif.
Medard's most famous institution was the Salency Rose Festival (the Rosière de Salency) — the medieval French Catholic civic-religious annual tradition in which the most virtuous young Christian woman of the small Picardy village of Salency (Medard's birthplace) was crowned each year on June 8 (Medard's feast day) with a crown of white roses and given a small dowry. The Salency Rose Festival has been observed continuously since around 540 AD, surviving the French Revolution, the Napoleonic period, and the modern French anti-religious legislative tradition. The Salency Festival is the oldest continuously-observed Catholic civic-religious festival in France, and is the example of the Catholic Christian-virgin civic-rosière tradition that spread across northern France in the medieval period.
Medard transferred his episcopal see from Vermand to the nearby small town of Noyon around 545 (the political collapse of Vermand during the Frankish wars forced the transfer); the new Noyon-Tournai see was governed by Medard until his death on June 8, 560. The Frankish King Clotaire I — the son of Clovis I — and most of the Frankish royal court attended Medard's funeral at Soissons, where the king built the great Royal Abbey of Saint-Médard at Soissons in his honour (the Royal Abbey was the royal-political-religious site of the Merovingian dynasty for the next three centuries, the site of the Frankish Royal coronations until Charlemagne).