re: #149 LudwigVanQuixote
Medical doctors are granted the rank of captain or full lieutenant (navy) automatically. After completing residency (i.e. more than four years in service), promotion to major is pretty standard. You would not want the chief of a medical department being outranked by his/her subordinate physicians.
Many MDs in the military leave as colonels.
My aunt (Combat Nurse, Vietnam) retired as a Lt. Col.
*Waves at Aunt Allie*