Definition
In old European law, a sudden military expedition or armed sally. The term denotes a rapid, offensive military foray — a quick strike rather than a sustained campaign or organized siege. It appears in medieval Latin legal and historical texts as a term of military organization and feudal obligation.
Why It Matters in Research
REISA is a term of narrow historical scope, relevant primarily to researchers working in medieval European law, feudal tenure, and the legal obligations attached to military service. It will surface in Latin legal texts, feudal charters, and chronicles concerned with the duties owed by vassals to lords — contexts where the distinction between different categories of military service (garrison duty, full campaign service, brief expedition) had legal and economic consequences.
Researchers should note that the term appears in highly specialized Latin-language sources and is unlikely to appear in English common law materials or post-medieval legal texts. If you encounter it in a source, treat it as a signal that the document is drawing on continental European or ecclesiastical legal tradition rather than English common law. Spelman's Glossarium Archaiologicum, cited by Burrill, is the primary English-language reference work for terms of this register and remains the most reliable source for contextualizing REISA within its period.
The term has no living legal meaning and no jurisdictional application in any modern legal system. Research use is confined to legal history, medieval studies, and the history of feudal military obligation.
Historical Dictionary Support
Burrill's Law Dictionary provides the sole entry among the shelf sources. Burrill defines REISA as "a sudden military expedition; a sally (procursus militaris)" and traces it to Saxon roots (ræse, a rush), citing Spelman as authority. The Latin label "procursus militaris" — a military advance or forward movement — confirms the sense of speed and limited duration that distinguishes reisa from a full military campaign (expeditio) or a siege operation.
No other shelf dictionary in the Law Mind corpus contains an entry for this term. The absence is expected: REISA is a term of medieval European legal Latin with no reception in English equity, common law, or statutory tradition. Black's Law Dictionary and similar common law reference works do not treat it. Researchers should not infer a broader legal significance from Burrill's inclusion — Burrill's scope extends deliberately to Roman, canon, and continental feudal law in a way that later American law dictionaries do not.
The Saxon derivation noted by Burrill (ræse) connects the term to the Germanic linguistic substrate of early medieval legal vocabulary, which may assist researchers cross-referencing cognate terms in Old English, Old Norse, or early Germanic law codes. However, etymology should not be used to impute legal meaning beyond what the Latin legal sources directly support.