Ælle (also Aelle or Ella) is recorded in much later medieval sources as the first king of the South Saxons, reigning in what is now called Sussex, England, from 477 to perhaps as late as 514.

[2] The chronicle goes on to report a victory in 491, at present day Pevensey, where the battle ended with the Saxons slaughtering their opponents to the last man.

[3] In the late 9th-century Anglo-Saxon Chronicle (around four hundred years after his time) Ælle is recorded as being the first bretwalda, or "Britain-ruler", though there is no evidence that this was a contemporary title.

Subsequently, a British leader named Vortigern is supposed to have invited continental mercenaries to help fight the Picts who were attacking from the north.

[10] The British thus gained a respite, and peace lasted at least until the time Gildas was writing: that is, for perhaps forty or fifty years, from around the end of the 5th century until midway through the sixth.

[11][12] Shortly after Gildas's time, the Anglo-Saxon advance was resumed, and by the late 6th century nearly all of southern England was under the control of the continental invaders.

[25][26] It is also noteworthy that there is a long gap between Ælle and the second king on Bede's list, Ceawlin of Wessex, whose reign began in the late 6th century; this may indicate a period in which Anglo-Saxon dominance was interrupted in some way.

Procopius, a Byzantine historian, writing not long after Gildas, adds to the meagre sources on population movement by including a chapter on England in one of his works.

He records that the peoples of Britain—he names the English, the British, and the Frisians—were so numerous that they were migrating to the kingdom of the Franks in great numbers every year,[30] although this is probably a reference to Britons emigrating to Armorica to escape the Anglo-Saxons.

It also seems consistent with the dates given to assume that Ælle's battles predate Mons Badonicus.This in turn would explain the long gap, of fifty or more years, in the succession of the "bretwaldas": if the peace gained by the Britons did indeed hold till the second half of the 6th century, it is not to be expected that an Anglo-Saxon leader should have anything resembling overlordship of England during that time.

[21] Procopius's account is consistent with what is known to be a contemporary colonization of Armorica (now Brittany, in France); the settlers appear to have been at least partly from Dumnonia (modern Cornwall), and the area acquired regions known as Dumnonée and Cornouaille.

[37] The battles listed in the Chronicle are compatible with a conquest of Sussex from west to east, against British resistance stiff enough to last fourteen years.

[38] The historian Guy Halsall argues that as Ælle immediately preceded a sequence of three contemporaries from the late sixth-century in Bede's original list (Ceawlin of Wessex, Æthelberht of Kent, and Rædwald of East Anglia), it is far more likely that Ælle dates to the mid sixth century, and that the Chronicle has moved his dates back a century in order to provide a foundation myth for Sussex which puts it chronologically and geographically between the origins of the kingdoms of Kent and Wessex.

[40] If Ælle died within the borders of his own kingdom then it may well have been that he was buried on Highdown Hill with his weapons and ornaments in the usual mode of burial among the South Saxons.