Bede, the first to mention Horsa, traces the brothers’ decent from a Saxon god, and names their father as Wihtgils.
Horsa led part of the Saxon army in Britain. He was killed fighting one of Vortigern’s sons (Vortimer, Catigern, or Vortiger) during Vortimer’s war against Hengist (some say a cousin of Vortigern), but managed to mortally wound his killer.
Historia Ecclesiastica Gentis Anglorum | Bede, 731
Anglo-Saxon Chronicle | 9th century
Historia Brittonum | Probably Nennius, early 9th century
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138
Roman de Brut | Wace, c. 1155
Brut | Layamon, late 12th century to mid-13th century