Medieval legal sources occasionally designate an oath of truce (German Urfehde) with the Latin terms caucio or confirmatio (a “guarantee” or “promise” under oath). In the Lexicon juridicum (1721) of Samuel Oberländers, a late contemporary of oaths of truce, describes them as “a kind of guarantee [Caution]” or an “assurance under oath” [3. 724 f.], with which the person swearing the oath of truce forewent vengeance or, originally, the further conduct of a feud. Modern scholars underst…