'' Offa of Mercia, who reigned from 757 to 796, was the dominant force in Anglo-Saxon England in the second half of the eighth century. The relationship between Offa and
Cynewulf, who was king of Wessex from 757 to 786, is not well documented, but it seems likely that Cynewulf maintained some independence from Mercian overlordship. Evidence of the relationship between kings can come from charters, which were documents which granted land to followers or to churchmen, and which were witnessed by the kings who had the power to grant the land.
Subregulus In some cases a king will appear on a charter as a
subregulus (subking or underking), making it clear that he has an overlord. Cynewulf appears as "King of the West Saxons" on a charter of Offa's in 772, and in 779, he was defeated at the
Battle of Bensington by Offa, but there is nothing else to suggest Cynewulf was not his own master, and he is not known to have acknowledged Offa as overlord. Offa did have influence in the southeast of the country: a charter of 764 shows him in the company of
Heahberht of Kent, suggesting that Offa's influence helped place Heahberht on the throne. The extent of Offa's control of Kent between 765 and 776 is a matter of debate amongst historians, but from 776 until about 784 it appears that the Kentish kings had substantial independence from Mercia. Another Ecgberht,
Ecgberht II of Kent, ruled in that kingdom throughout the 770s; he is last mentioned in 779, in a charter granting land at
Rochester. Ealhmund does not appear to have long survived in power: there is no record of his activities after 784. There is, however, the extensive evidence of Offa's domination of Kent during the late 780s, with his goals apparently going beyond overlordship to outright annexation of the kingdom, It is possible that the young Ecgberht fled to Wessex in 785 or so; it is suggestive that the
Chronicle mentions in a later entry that
Beorhtric, Cynewulf's successor, helped Offa to exile Ecgberht. The
Anglo-Saxon Chronicle records that Ecgberht spent three years in Francia before he was king, exiled by Beorhtric and Offa. The text says "iii" for three, but this may have been a scribal error, with the correct reading being "xiii", which is thirteen years. Beorhtric's reign lasted sixteen years, and not thirteen; and all extant texts of the
Chronicle agree on "iii", but many modern accounts assume that Ecgberht did indeed spend thirteen years in Francia. This requires assuming that the error in transcription is common to every manuscript of the
Anglo-Saxon Chronicle; many historians make this assumption but others have rejected it as unlikely, given the consistency of the sources. In either case Ecgberht was probably exiled in 789, when Beorhtric, his rival, married the daughter of Offa of Mercia. At the time Ecgberht was in exile, Francia was ruled by Charlemagne, who maintained Frankish influence in Northumbria and is known to have supported Offa's enemies in the south. Another exile in Gaul at this time was Odberht, a priest, who is almost certainly the same person as
Eadberht, who later became king of Kent. According to a later chronicler,
William of Malmesbury, Ecgberht learned the arts of government during his time in Gaul. == Early reign ==