The American use of bellum, the Latin word for war, is interesting. In American history, the antebellum and postbellum periods are the pre- and post-Civil War, respectively. Neither word is associated with any other war, just the Civil War.
Also interesting is that bellum doesn’t have its own entry in either Merriam-Webster’s Collegiate Dictionary (11th ed.) or the American Heritage Dictionary (4th ed.); the entries are either antebellum or postbellum.
I’ve been word sleuthing, trying to discover definitively why Americans associate bellum only with the ante and post Civil War time frames; why not, for example, ante- and post-Vietnam War? My guess is that newspapers and magazines of the post-Civil War era used the phrases and they became associated with those eras.
In 1867, the Fredericksburg News (Fredericksburg, VA) ran a headline “Attention, Ante Bellum Debtors to the News.” In 1878, the North American Review wrote: “To go back to Ante-war money, Ante-war wages, and ante-war prices, might be tolerable if, at the same time we could go back to ante-war freedom from debt and ante-war lightness of national taxation.” Southern Magazine (1874) wrote of Atlanta: “It looks so little like a post-bellum town.”
Although bellum simply means war and antebellum and postbellum can be used to describe and pre- and post-war period, American usage of these terms appears to be confined to the pre- and post-Civil War periods because of the impact the Civil War had on both American history and American psyche. Limiting words to specific time frames gives structure to the words.
Using a Latin substitute, bellum, for an English word, war, probably would be rejected by many Americans. The Middle English origins of war (werre) indicate a long rejection of bellum for everyday discourse (imagine hearing, “We’re off to bellum!” — it doesn’t strike a very war-like chord — or “Bellum! Bellum! Bellum!”). But antebellum and postbellum, as descriptors of a 30-year period on either side of the Civil War, strikes a better sounding chord, especially when joined with south.
If someone has a better idea or more information on why and how antebellum and postbellum became associated with 1830-1861 and 1866-1890 eras of American history, let me know.