"Expire" is way too nice of a word to describe what "crève" means. "Crever" can be used for tires (to puncture/burst a tire). In this case it means "to die", but is very vulgar. I don't think there's a good English translation for it. The correct translation would be "Walk or die". (source: native French speaker)
The comparison to "sink or swim" is understandable, however sink or swim is "fail or succeed". "Marche ou crève" basically means "get in line or be left to die", meaning the society.
In the Military it is a term much like "Keep moving forward, or be left to die". Similar to what was said before, but the onerous is on the individual. Very often the battlefield is littered with men who gave up, or couldn't keep up. Modern warfare makes a lot of these motto's irrelevant, but they are inspiring. MonsieurET (talk) 03:52, 13 January 2018 (UTC)