In 893, Asser wrote this book, a biography of Alfred the Great entitled The Life of King Alfred; in the original Latin, the title is Vita Ælfredi Regis Angul Saxonum. The date is known from Asser's mention of the king's age in the text. The work, which is less than twenty thousand words long, is one of the most important sources of information on Alfred the Great, King of the West Saxons from 871 to c. 886 and King of the Anglo-Saxons from c. 886 until his death in 899. He is well-known for overseeing the conversion of Viking leader Guthrum to Christianity, and defending his kingdom against the Viking attempt at conquest, leading him to become the dominant ruler in England.