It is quite possible "deadline" has two separate origins. There's the unquestioned Civil War usage, but the phrase dropped out of use for 50 years before showing up again as the time a newspaper had to be "dead" in order for the presses to start printing it.

So in both cases, it's a line (literal or figurative) you can't cross without horrible consequences, but it isn't clear the first usage led to the second one.

https://web.archive.org/web/20131016215332/http://www.randomhouse.com:80/wotd/index.pperl?date=20000420

Freelance writer and data scientist in Metro Detroit. Covered pro sports for NHL.com and the Associated Press before COVID-19. Mentally ill and not ashamed.

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