The mount gained strategic significance again in 933 when William I Longsword annexed the Cotentin Peninsula from the weakened Duchy of Brittany. This made the mount definitively part of Normandy, and is depicted in the Bayeux Tapestry, which commemorates the 1066 Norman conquest of England. Harold Godwinson 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.