In my earlier post I meant to emphasize that Surgeons and Assistant Surgeons usually have two different service files. Of course one of those would be filed with the unit to which they were assigned. The other would be found with M331, as mentioned earlier. The latter is the right place to look for appointments, promotions and assignments.

Appointments of medical officers usually include the physician's middle name and his state of residence. Like all other commissioned officers, there are three dates associated with each appointment or promotion. First is the date of appointment, meaning the date the appointment or nomination was recorded by the War Department. Second is the date of rank. This is the date the officer actually begins to hold rank, and is important for payroll purposes. Third is the date of acceptance. Each commissioned officer received notification of appointment or promotion from the War Department, which required the officer's signature showing that he had accepted the office.

If you're only using the Mississippi unit file for service documentation, as a general rule you should expect to have a fraction of the information available for the staff officer in question.