The 33rd Illinois Infantry was originally formed from many college students on the campus of the Illinois State Normal School and became known as the "Teacher's Regiment". In one company there were 13 college graduates and all were privates. The soldiers were so well educated that the standard joke was that men discharged for mental incapacity would have made officers in other regiments. The unit formally organized between 15 August and 29 September 1861 at Camp Butler near Springfield, Illinois, and mustered into federal service on 3 September 1861.