Vortigern makes use of Hengist and Horsa, brothers and legendary leaders of the first Anglo-Saxon settlers in Britain who emigrate, according to the English historian and theologian Bede, to fight for the British king against the Picts.

The brothers are said to have been Jutes and sons of one Wihtgils.

The Anglo-Saxon Chronicle says that they landed at Ebbsfleet, Kent.

The Angles, Saxons and Jutes, members of the three tribes of northern Germany and southern Denmark (present Schleswig-Holstein),  beginning in about 450 join in the widespread migrations of the age and cross the North Sea to seek new homes in a Britain now unprotected by Roman legions.

Nonroyal tyrants have begun to take control of various territories in Britain.

One such, a Briton named Vortigern, hires a large group of the would-be colonists from northern Germany and southern Denmark, along with a number of Frisians and some Franks, to fight the Picts, offering land in Kent as a reward.

These continental mercenaries rebel, demand additional territory, and send for their relatives, who help them to win victories against the Britons in about 455 at Aylesford and in about 457 at Crayford.

The Germanic dialects of the Jutes, Angles, and Saxons are the foundation of the Old English language.

Vortigern receives the Saxon leaders Hengist and Horsa, by tradition leaders of the Jutes, "as friends" and grants the brothers the Isle of Thanet, the most easterly point of Kent (England).

The Anglo-Saxons begin a conquest that is facilitated by an epidemic plague and weakens the country.

The ninth-century Anglo-Saxon Chronicle mentions the battle of Aylesford in the entry for 455.

According to the text, the Anglo-Saxon leaders Hengist and Horsa fought Vortigern, King of the Britons, in the battle.

Horsa was slain, and Hengist and his son Oisc became the Kings of Kent.

The Historia Brittonum, also written in the ninth century, contains a variant account of the battle.

Chapters 43–45 indicate that Vortigern's son Vortimer, not Vortigern himself, rose against the Saxons and engaged them in four battles.

The third of these battles was fought "at the Ford, in their language called Epsford, though in ours Set thirgabail”.

At this battle Horsa falls, as does Vortimer's brother Catigern.

The Historia does not say who won the battle, saying specifically that during Vortimer's campaign the Saxons "sometimes extended their boundaries by victory, and sometimes were conquered and driven back."

According to the text, the Britons successfully ousted the Saxons at the fourth battle, fought "near the stone on the shore of the Gallic sea".

However, Vortimer's death shortly after ensures the victory is short lived.

The Anglo-Saxon Chronicle account is similarly grim for the Britons, saying that they were forced to forsake Kent for good in 457 following Hengist and Oisc's bloody victory at Crayford.