The poem describes a historical event involving a battle between the Danish prince Hnæf and several of his warriors, and Finn, lord of the Frisians and of the manorhouse (or burh) where the battle took place.
The events of the poem are also described in passing in Beowulf.
In both accounts, a fight breaks between Danes and Frisians during a visit by Hnæf and his sixty warrors to Finn's hall. The idea of a bloody battle between a host and his guests probably served as a powerful plot device to the contemporary Germanic audience, and the fact that Hnæf's sister Hildeburh was Finn's wife provides even more dramatic tension.
In the ensuing battle, both Hnæf and his nephew (Finn and Hildeburh's son, a Frisian) are killed. Grieving, Hildeburh has the bodies of her son and brother burned together on the same funeral pyre, despite their having fought on opposite sides.
Afterwards, Hnæf's lieutenant Hengest vows revenge for his lord's death and succeeds in killing Finn.
The Finnesburg Fragment is a fragment of an Old English poem of the type called a leoð, or "lay." The existing text is a transcript of a loose manuscript folio that was once kept at Lambeth Palace, the London residence of the Archbishops of Canterbury; the manuscript was almost certainly Lambeth Library MS 487.
The fragment begins with Hnaef's observation that what he sees outside "is not the dawn in the East, nor is it the flight of a dragon, nor are the gables burning"; what he sees is the torches of approaching attackers.
The fragment contains no Christian references, and the burning of Hnaef is clearly pagan; it is short and about a battle, but the two fragments of the battle-poem Waldere manage to be explicitly Christian in hardly more space.