Shortly after the Battle of Fort Sumter, President Lincoln called for 75,000 volunteers.

There they were mustered in by Captain John Pope on April 26, 1861, and formed into the 9th Regiment, Illinois, volunteer infantry.

The regiment was moved to Cairo for garrison duty near the Mississippi River until July, 1861.

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

On 9 July 1865 the 9th Illinois Infantry was mustered out (released from military service) at Louisville, Kentucky.

[8] The regiment suffered 5 officers and 211 recruited men killed in action or mortally wounded.

[9] The 9th Illinois volunteers, along with the 8th, 11th, and 12th, all wore gray coats trimmed in blue.

[10] Most of the Illinois infantry regiments were issued the Springfield Model 1861 muskets.