Brigadier General Joshua Chamberlain was a Brevet Major General
So what was a brevet and how did it work? An explanation can be as confusing as it became for the Federals during the war itself. For example, you could be a colonel and because of some heroic deed on the battlefield and you would be receive a promotion to brevet brigadier general. Actually you were still a colonel, you did not receive a pay promotion or assume brigade command. The promotion was in name only, almost like a reward. That sounds simple enough, but lets look at some of the more complicated things that came along with that.
There were more than just one army within the Federal military structure (I hope I'm saying that right). For example, since the regular army was so small at the beginning of the war, volunteers were raised, therefore you had the regular army and the volunteer army. You could be a regular army colonel and be a brevet brigadier general, but at the same time you could be a brigadier general of volunteers with a brevet rank of major general. Are you confused yet?
Robert E. Lee always wore the stars of a colonel
In the Confederate army, there was no brevet system in place. Although, at times the word brevet rank is mentioned, its an entirely different system than the Federals. If the word brevet was used in the Confederate army, it was usually because someone was temporarily promoted to hold a higher position. It was rarely used. Lee always wore the rank of colonel, because the Confederate army was also a volunteer army. Although Lee was a full general of volunteers, he was a regular army colonel. The brevet system in the Federal army caused confusion by adding to an already confusing situation.
The Heroic Army Mule/Horse
During the night battle at Wauhatchie near Chattanooga, some Federal army mules panicked by the gunfire charged into part of the Confederate lines. The Confederates thought it was a cavalry charge and fell back temporarily. Following the battle, a telegrapher sent a message to Washington poking fun at the confusing brevet system and its over use. He recommended that those heroic mules be breveted up to the rank of horses. What the authorities in Washington thought of this recommendation has not been recorded.