casus belli

See also: Casus Belli

English

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casus belli

Etymology

From Latin cāsus (“case”) + bellī (“of war”). The English homographic plural casus belli is also taken from Latin, where the plural of this phrase would be cāsūs bellī, with a long vowel ū in the first word, as is typical of the nominative plural of fourth-declension nouns.

Pronunciation

IPA^(key): /ˈkeɪ.səs ˈbɛl.aɪ/, /- ˈbɛl.i/
(plural) IPA^(key): /ˈkeɪ.suːs ˈbɛl.aɪ/, /- ˈbɛl.i/

Noun

casus belli (plural casus belli or casus bellis)

An act seen as justifying or causing a war; an act of war.
- 1897, Congressional Record, U.S. Government Printing Office, page 664:
  The Executive, however, can do many acts which would constitute a casus belli, and thus indirectly result in war; but this does not imply in the Executive a concurrent power to declare war, and the war which would result would be one declared by a foreign power.
- 1977, Alistair Horne, A Savage War of Peace, New York: Review Books, published 2006, page 309:
  Algiers seethed, and this was the casus belli for the ‘ultras’ to attempt a general strike.
- 2002, Colin Jones, The Great Nation, Penguin, published 2003, page 138:
  Furthermore, if the French had airily waved away one potential casus belli, more than enough causes of potential conflict remained embedded in the Aix-la-Chapelle Treaty.
- 2010, Christopher Hitchens, Hitch-22, Atlantic, published 2011, page 290:
  Had Saddam taken only the Rumaila oil field and the Bubiyan and Warba islands, there would have been no casus belli.
- 2022 March 1, Mary Elise Sarotte, “I’m a Cold War Historian. We’re in a Frightening New Era.”, in The New York Times‎, →ISSN:
  And Washington needs to communicate clearly with not only its allies but also the American public on the risks involved if spillover from Ukraine into Article 5 territory verges on a casus belli — an event that provokes a war.