The infantry regiment was organized at Springfield, Illinois, and mustered in on April 25, 1861, for a three-month service.

Companies' "B" and "C" formed part of an expedition from Cairo to Little River on June 22 and 23rd.

Among the notables that served in the regiment was Major Hermann Lieb, who later commanded the Union forces at the Battle of Milliken's Bend.

The three-month 7th Illinois Volunteer Infantry Regiment was organized at Springfield, IL and served in the Department of the Missouri.

[1] The three-year 7th Illinois Volunteer Infantry Regiment was organized at Cairo, IL and served with the following organizations:[1] The 7th Illinois fought in the following battles:[1] The regiment's detailed service and locations are as follows:[2] The regiment suffered 6 officers and 160 enlisted men killed in action or died of wounds and 155 enlisted men who died of disease, for a total of 321 fatalities.