FROM DOT TO DOMESDAY
The title BRETWALDA appears in the ‘Anglo-Saxon Chronicle’, against the year 827, and translates as ‘ruler of Britain’.* The ‘Chronicle’ itself provides the 8th holder, Ecgberht, king of Wessex (r.802–839), whilst quoting the previous seven from Bede's ‘Historia Ecclesiastica’ (Book II Chapter 5):
  • Ælle of Sussex (r.477–514?)
  • Ceawlin of Wessex (r.560–591)
  • Æthelberht of Kent (r.560–616)
  • Rædwald of East Anglia (r.?–624?)
  • Edwin of Northumbria (r.616–632)
  • Oswald of Northumbria (r.633–641)
  • Oswiu of Northumbria (r.641–670)
Bede, who makes no mention of the word Bretwalda, or, indeed, any other title, says that these seven kings:
“... ruled over all the southern provinces that are divided from the northern by the river Humber and the borders contiguous to it ...”
‘Historia Ecclesiastica’ Book II Chapter 5
The ‘Chronicle’ substantiates this geographical distinction when describing Ecgberht, who, it asserts:
“... conquered the Mercian kingdom, and all that is south of the Humber, being the eighth king who was Bretwalda.”
Obviously, those Bretwaldas who were kings of Northumbria would, by default, also rule territory north of the Humber, but Bede notes that Edwin:
“... had the overlordship over all the nations who inhabit Britain, both English and British, except only the people of Kent ...”
‘Historia Ecclesiastica’ Book II Chapter 5
Furthermore, Bede states that, at the time of his writing (731), the:
“... southern provinces, as far as the boundary formed by the river Humber, with their several kings, are subject to King Æthelbald.”
‘Historia Ecclesiastica’ Book V Chapter 23
Yet he does not include Æthelbald (of Mercia, r.716–757) in his list, nor Æthelbald's predecessor, Wulfhere (r.658–675), who might be supposed to have fitted the bill. In the period after Bede's death, the ‘Chronicle’ doesn't consider Offa of Mercia (r.757–796) to be suitably qualified. Just what constitutes a ‘ruler of Britain’ is, therefore, not easy to state categorically.
Translations:
‘Anglo-Saxon Chronicle’ by James Ingram/J.A. Giles
Bede ‘Historia Ecclesiastica Gentis Anglorum’ by A.M. Sellar
Actually, the form Bretwalda only appears in Manuscript A (and G). The other manuscripts have various spellings of the form Brytenwalda. Whilst the former is translated as ‘ruler of Britain’, the latter might mean ‘wide-ruler’. It is thought likely that Brytenwalda is the correct form.