These terms all indicate a monetary unit of uncertain value and obscure origin, but Du Cange is doubtless correct in assuming that the French, Anglo-Saxon, and Latin forms are related. The earliest occurrence of mancus (or mances) in England dates from 848; the Latin mancus is found on the Continent as early as 814. The authorities are agreed that the Anglo-Saxon form came to Britain from the Continent. For me the main point of interest in this discussion is Old French mangon, best known through its first occurrence—in the Chanson de Roland:
Tenez m'espee, meillur nen at nuls horn,
Entre les helz ad plus de mil manguns.
Godefroy defines it as a “sorte de monnaie d'or: il fallait deux besantz pour faireun mangon.” This estimate of value was certainly taken from the fabliau of Guillaume au Faucon:
Dist la dame, “Or avez faucon;
Deux besans va'ent un mangon.”