Mont-Saint-Michel was used in the 6th and 7th centuries as an Armorican stronghold of Romano-Breton culture and power, until it was ransacked by the Franks, thus ending the trans-channel culture that had stood since the departure of the Romans in AD 460.
Before the construction of the first monastic establishment in the 8th century, the island was called "monte tombe". According to legend, the Archangel Michael appeared to St. Aubert, bishop of Avranches, in 708 and instructed him to build a church on the rocky islet. Aubert repeatedly ignored the angel's instruction, until Michael burned a hole in the bishop's skull with his finger.
The mount gained strategic significance in 933 when William "Long Sword", William I, Duke of Normandy, annexed the Cotentin Peninsula, definitively placing the mount in Normandy. It is depicted in the Bayeux Tapestry which commemorates the 1066 Norman conquest of England. Harold, Earl of Wessex is pictured on the tapestry rescuing two Norman knights from the quicksand in the tidal flats during a battle with Conan II, Duke of Brittany. Norman Ducal patronage financed the spectacular Norman architecture of the abbey in subsequent centuries.
In 1067, the monastery of Mont-Saint-Michel gave its support to duke William of Normandy in his claim to the throne of England. It was rewarded with properties and grounds on the English side of the Channel, including a small island off the southwestern coast of Cornwall which was modeled after the Mount and became a Norman priory named St Michael's Mount of Penzance.
During the Hundred Years' War, the English made repeated assaults on the island, but were unable to seize it due to the abbey's improved fortifications. Les Michelettes – two wrought-iron bombards left by the English in their failed 1423–24 siege of Mont-Saint-Michel – are still displayed near the outer defense wall.
When Louis XI of France founded the Order of Saint Michael in 1469, he intended
