I finished my classes for the semester this morning so I decided to watch a movie I was curious about but not too heavily invested in. Netflix suggested The Eagle, which seems to be a solid "C" sword and sandals film.
In the first few scenes of the movie a Centurion takes command of a cohort in Britannia. Celts attack his garrison, which because of his decisions ends in only a handful of causalities. During this battle the centurion is badly injured in the knee and he is sent away for medical attention.
Some time later, one of the officer's below him visits. He brings news that the cohort received a Golden Laurel for their standard and the centurion in particular receives a commendation of some sort. He is also informed that he has been honorably discharged because of his injury. The centurion clearly still desires to remain in the legion. He goes on to make a full recovery after being attended by a surgeon, and the movie continues onward.
Was it common for Roman soldiers, particularly centurions, to be discharged because of an injury? Or was this simply a plot device in the movie, or perhaps in actuality he never would have recovered from such a wound outside of hollywood.
There was no such thing as a non-combat posting in a legion in a sense, because all men, even engineers, were expected to fight (although doctors could have been exempt from this as it is not clear if they were actually legion members or just attached to the legion). In terms of what might happen to a centurion, this is a role that is definitely a combat one, and if you are an invalid, you will not be able to fight of course. Discharge due to medical conditions was called missio causaria. However, this was a very serious thing, and getting back into the army would not have been easy. That said, if a soldier simply needed recovery time as was the case in this film, they wouldn't have been proactively discharged.
If you're interested in more, here's a pretty good excerpt about this: