The Four Sons of Aymon

The Four Sons of Aymon, sometimes also referred to as Renaud de Montauban is a medieval tale spun around the four sons of Duke Aymon: the knight Renaud de Montauban, his brothers Guichard, Allard and Richardet, their magical horse Bayard, their adventures and revolt against the emperor Charlemagne. The story had a European success and echoes of the story are still found today in certain folklore traditions.

Source: Wikipedia