"Brevet" means a meritorious promotion, for bravery, sucessful completion of an unusual or dangerous assignment, rather than a regular promotion based on seniority or time in grade. When hostilities end, some breveted officers are returned to permanent grade, though they might be addressed with the higher grade. For instance, General Custer was a major general during the war, while his permanent grade was Lt. Colonel. All his promotions were not brevets, but were based on assignments. Alan or Gerald can explain this better, I'm sure, but I happened to see your question. Stan