Bath may have been the site of the Battle of Badon ( 500 AD ), in which King Arthur is said to have defeated the Anglo-Saxons. The town was captured by the West Saxons in 577 after the Battle of Deorham; the Anglo-Saxon poem "The Ruin" may describe the appearance of the Roman site about this time. A monastery was founded at an early date – reputedly by Saint David although more probably in 675 by Osric, King of the Hwicce, perhaps using the walled area as its precinct. Nennius, a 9th-century historian, mentions a "Hot Lake" in the land of the Hwicce along the River Severn, and adds "It is surrounded by a wall, made of brick and stone, and men may go there to bathe at any time, and every man can have the kind of bath he likes. If he wants, it will be a cold bath; and if he wants a hot bath, it will be hot". Bede described hot baths in the geographical introduction to the "Ecclesiastical History" in terms very similar to those of Nennius. King Offa of Mercia gained control of the monastery in 781 and rebuilt the church, which was dedicated to St. Peter.