The "Grand Army of the Republic" was the name attached to the group of Veterans of the Army of the Potomac (the North). GAR was not the name of the Union Army during the war. Just one little change here, the GAR was for all northern army veterans, not just those of the AOP. Also, there was an organization just for officers - Military Order of the Loyal Legion of the United States(MOLLUS). So for those who are very looking for info, if your ancestor was an officer, he might have been a member of MOLLUS. Paula