Æthelwealh of Sussex Æthelwealh ( " fl . " c . 660 – 685 ) ( also written Aedilualch , Aethelwalch , Aþelwold , Æðelwold , Æþelwald , or Ethelwalch ) was the first historical king of Sussex . Æthelwealh became the first Christian king of Sussex and was king when Sussex was converted to Christianity in 681 . In 661 , Æthelwealh received the territories of the Meon Valley in modern - day Hampshire , and the Isle of Wight from his godfather , Wulfhere , king of Mercia . Æthelwealh was killed in around 685 by Cædwalla , at the time a prince of the Gewisse tribe of modern - day Oxfordshire , who had been operating as bandit in Sussex . All known information about him comes from brief mentions in Eddius ' s " The Life of Bishop Wilfrid " , Bede ' s " Ecclesiastical History of England " , and " The Anglo - Saxon Chronicle " . Æthelwealh was the third recorded ruler of the South Saxons in Sussex . The Anglo - Saxon Chronicles record Aelle as both the first Bretwalda and king of the South Saxons , although Slaughter refers to Bede on ancestral Saxon aldermen and argues that Aelle was probably the South Saxon Warlord ( Rulers of the South Saxons before 825 ) . The second ruler of the South Saxons in Sussex is recorded by Roger of Wendover as King Cissa . So Æthelwealh was the third recorded ruler of the South Saxons in Sussex . The Kingdom of the South Saxons was devolved on Ceawlin of Wessex on Cissa ' s death ( Roger of Wendover ) and he would have been the overlord in Sussex . An emendation in the Wendover text from ' died in 590 ' to ' died aged 90 ' would give a date of 567 for the devolvement on Wessex , assuming Cissa was born in 477 ( Slaughter ) . A case can be made ( Slaughter ) that Æthelwealh was installed by Penda in 645 , when Cenwalh was driven out of his kingdom by Penda for divorcing the latter ' s sister . According to Roger of Wendover Sussex was devolved on Ceawlin of Wessex after the death of King Cissa . There is no reason to suppose this devolvement did not continue under Ceawlin ' s successors and yet Æthelwealh is recorded as the King in Sussex in 661 . Cenwalh is unlikely to have given up his guardianship of Sussex , as its borders were too near his royal centre at Winchester . According to Saxon dooms , recompense depended on the status of the offended person . Cenwalh had deprived Penda ' s sister of her queenly status , and a just recompense when Penda invaded Wessex would have been for him to have deprived Cenwalh of the kingdom in Sussex . Penda was a decisive man . There is also a case to be made that Æthelwealh was a son of Cynegils . The case is based on There is another case to be made for an Aethelwalhan dynasty . This is illustrated by comparing the earlier " Æthel - eald " dynasty that appears to be found in Sussex with the later " Æthel - ælf " dynasty that ruled over Wessex . There could perhaps be other members of this dynasty who were Æthelwealh ' s natural sons . They were aldermen who held high status in Sussex : King Watt , Æthelwealh ' s personal aldermen Berhthun and Andhun , and Bryni Duke of the South Saxons . Moreover their names alliterate , suggesting that they were indeed brothers . If we assume that Æthelwealh was an elder brother of Centwine and Aethelwine , then he could have been born in the early 620s . If we also assume that it was in 661 Æthelwealh married Eafe , on the insistence of Wulfhere , then it is possible that he had lived with a concubine by whom he had earlier sons . See Slaughter , Rulers of the South Saxons before 825 . Æthelwealh became a Christian while in Mercia where the King of Mercia , King Wulfhere , sponsored his baptism . At this time the people of Sussex were pagans . In 661 , Wulfhere gave Æthelwealh the territories of Meonwara and the Isle of Wight . Æthelwealh ' s queen was Eafe ( also written Eabae or Ebba ) , the daughter of Eanfrith ( Eanfrid or Eanfridi ) , a ruler of the Christian Hwicce people . Wilfrid , the exiled bishop of York , came to Sussex in 681 and converted the people to Christianity with King Æthelwealh ' s approval . Æthelwealh gave Wilfrid land in Selsey where he founded Selsey Abbey . Wilfrid , however met with Caedwalla a prince of the Gewisse , then operating as a bandit in Sussex , and came to a mutual agreement to advance one another ' s interests . According to Bede , in 686 , Cædwalla invaded South Saxon territory and killed Æthelwealh . Cædwalla was then driven out by two of Æthelwealh ' s ealdormen , Berhthun and Andhun . When Cædwalla became King of the West Saxons , the following year , he conquered Sussex and appears to have appointed an Ecgwald as a sub - regulus ( on cartulary evidence ) . His name means " noble foreigner " , which indicates that he might have been a Saxo - Briton nobleman as might have been Cenwealh Cynegilsing , earlier King of the West Saxons ( A - S Chronicles ) . According to tradition , Cædwalla invaded Sussex and was met by Æthelwealh at a point in the South Downs just south - east of Stoughton , close to the border with Hampshire and it was here that Æthelwealh was defeated and slain . According to the same tradition , Æthelwealh lies buried in the southern barrow of the group that marks the spot .