I am not sure about the military use coming from the theatrical. My understanding is that staging means 'standing place', and that the theatrical stage is just

I am not sure about the military use coming from the theatrical. My understanding is that staging means 'standing place', and that the theatrical stage is just 'something to stand on'. You sometimes get scaffolding called staging in the UK. The military use has the same root but is not derived from the theatre I beleive. A staging area is somewhere you stand and wait. Very similar in use to the staging-posts that a stage-coach goes through. The meaning in git could mean directly this, somewhere to wait, or it could be derived from the further development of the process stages. The stage having become the journey itself rather than the stopping-point. Something is staged because you have completed a stage and are waiting to start the next stage. That is rather circular really. At this stage I will pass you over to an article https://en.wiktionary.org/wiki/stage https://en.wiktionary.org/wiki/stage