The Sword in the Stone

The story is set in a fictional England somewhat resembling that of the 15th century. When King Uther Pendragon dies leaving no heir, a sword magically appears in an anvil, itself embedded in a stone, with an inscription proclaiming that whoever removes the sword is the rightful King of England. None succeed in removing the sword, which eventually becomes forgotten, leaving England in a situation akin to the Wars of the Roses.