"You see, I think the biggest problem with your reasoning is that the Army don't do short term detachments for operation duties"
You are conflating two things - I mean 'detachment to go and do jobs elsewhere, be it course, augmentation for an exercise, detachment to go and work in another organisation for 6 weeks, or all manner of other operational duties that Soldiers can and do engage in' (all of those examples have happened to soldiers who have worked with, or for, me).