I've been following with interest the imput on Civil War military organization. Seems I remember from reading Civil War history much about military unit formation is referred to by "Brigades", most noted is at the Battle of Gettysburg. I remember from my service in the Korean War period the Brigade formation was not in use as it is today. From what I experienced it was mostly squads, platoons, company, battalion, regiment, division, corps --as has already been mentioned. Since I live next to Fort Drum and the 10th Mountain light infantry division,(rapid deployment), the organization term "Brigade" is commonly used in today's army. It seems that there are 4 Brigades to a full combat Division w/ support units.