Complex sentence: Within a month it was determined that he had initially requested to be A-O-1, so he could serve as a non-combat medic, but the military's policy that service men cannot request or be guarenteed where they serve force him to request 4E status.
Split into simpler sentences: Within a month it was determined that he had initially requested to be A-O-1, so that he could serve as a non-combat medic. However, the military's policy that service men cannot request, or be guaranteed where they will serve, forced him to request a 4E status.