Sorry if this is a silly question gents but I wasn't able to find aything on Arrsepedia or the wider internet on the subject. So, I've read that such-and-such a unit is being backfilled by troops from other units while on Ops a few times, and I was wondering how exactly this works, say, is it voluntary or are soldiers ordered into it? If so is it something your average Infantryman would be expected to do, or is it more often done by specialists and such? I ask because I will be joining the Royal Irish Regiment after I pass out sometime in November (all things going according to plan), which would be a short while after they are set to return from Op Herrick, and I wonder if the longer wait before I would normally be deploying with my Battalion (again, all things going according to plan) would make me a candidate for backfilling another unit, if that is indeed how it works. Anyway this is wild speculation on my part but I suppose I'd like to do my fair share once I've got through Catterick. Thanks in advance for any help you guys can offer.