Ah OK...I wasn't considering the draft in your response.
Still, my position would be that whether you are a volunteer or a draftee makes no difference once you are in the military. As you know, although serving in the military is voluntary in the U.S., once a person joins they are no longer free to do as they please as they would be in a civilian job. They are obligated to complete the contract they sign and until their "hitch is up" they do what they are ordered to do. All military personnel are guided by orders which determine where and when they go anywhere, such as in this case apparently. The person would have received written orders directing him/her to report for duty to a specific location at a specific time and date and that person carries those orders from one command to the next. Failure to obey those orders would result in disciplinary action. To put it another way, the person is being
commanded to report for duty. I don't know what Spanish word other than "ordenes" would convey that "do it or else" condition.
Saludos!
Saludos