Carmen de Hastingae Proelio
The Carmen de Hastingae Proelio (Song of the Battle of Hastings) is an early written source for the Norman invasion of England from September to December 1066, in Latin; attributed to Bishop Guy of Amiens, uncle to Count Guy of Ponthieu, who figures rather prominently in the Bayeux Tapestry as the vassal of Duke William of Normandy who captured Harold Godwinson in 1064.
The Carmen is generally accepted as the earliest known written account of the invasion and focuses on the famous Battle of Hastings, although it also offers insights into navigation, urban administration and ecclesiastical influence. It is in poetic form, 835 lines of hexameters and pentameters, and is preserved only in a single extant copy (Bibliothèque royale de Belgique no. 10615-729, folios 227v-230v), which is apparently an early 12th century copy of the 11th century original.
Bearing all the signs of hasty work, the Carmen was most likely composed within months of the coronation of William as king of England (Christmas Day, 1066)—probably sometime in 1067, possibly as early as Easter of that year, to be performed at the royal festivities in Normandy, where King William I presided. The motivation for the poem's production and performance must have been something to do with Bishop Guy's family, which possibly was then out of favour over the involvement of Hugh of Ponthieu in the death of King Harold and the senior family's attempts to assassinate the young duke in childhood. Some have suggested Hugh was the perpetrator of the mutilation of King Harold once he had been slain, although others suggest there was no mutilation as the severed leg was waved merely to signal an end to combat with the death of King Harold. Also, at the time, Bishop Guy himself was out of favour with the pope, and perhaps wanted to garner some Norman influence by giving William the gift of the Carmen in his honor and inviting Lanfranc of Pavia, abbot of Abbey of Saint-Étienne, Caen and later archbishop of Canterbury (to whom the Proem of the poem is dedicated) to use his influence with king and pope. A third possibility (though none of these are mutually exclusive), is the disfavour of Eustace, Count of Boulogne, who appears by the contents of the Carmen, to have been a family friend (and or relative: most of these noble houses were intermarried by this time), therefore the Carmen might have been composed to present Count Eustace in a favourable light and thus possibly reverse King William's banishment of Count Eustance following his failed invasion of England in the autumn of 1067 (Eustace remained in fact out of favour until late in the 1070s).
Altogether, the Carmen is the most vivid of the original written accounts, and practically the only one to give a non-Norman point of view in detail. The Bayeux Tapestry is problematic; the identity and purpose of its creators is unknown, though it bears evidence of English involvement in its production.  In fact, it is the Carmen's very vividness which has caused it in the past to come under attack as either a forgery, fraud or at the least a later, 12th-century source. But Frank Barlow argues in support the position of the Carmen as a very early source indeed, most likely from the year 1067.
- Carmen de Triumpho Normannico - The Song of the Norman Conquest, transcribed from digital images of the manuscript and translated by Kathleen Tyson, Granularity Press 2014. 
- The Carmen de Hastingae Proelio of Guy Bishop of Amiens, edited by Catherine Morton and Hope Muntz, Oxford at the Clarendon Press 1972.
- The Carmen de Hastingae Proelio of Guy Bishop of Amiens, edited and translated by Frank Barlow, Clarendon Press 1999.
- Davis, R. H. C. 1978. 'The Carmen de Hastingae Proelio'. The English Historical Review Vol. 93, No. 367, pp. 241-261 JSTOR