C. Carroll Marsh

Due to the reputation of the Chicago Light Guard, Captain Marsh was called to Springfield, Illinois at the outset of the Civil War. Eager to offer his services, he responded quickly and was given command of the 20th Illinois Volunteer Infantry Regiment.[4] Colonel Marsh and his command were transported to Cape Girardeau, Missouri and attached to Colonel Joseph B. Plummer's command at the Battle of Fredericktown.

Position of Marsh (WHL Wallace's Brigade) on the morning of February 15

Colonel Marsh and the 20th were stationed at Bird's Point, Missouri until joining Ulysses S. Grant's expedition to Fort Henry as a part of W. H. L. Wallace's 2nd Brigade in John A. McClernand's 1st Division. At the battle of Fort Donelson Marsh was positioned on the right of the Union lines. McClernand's entire division was hit hard during the Confederate breakout attempt on February 15. Despite being hard pressed Marsh managed a counterattack which momentarily checked Simon B. Buckner's division and saved an Illinois artillery battery from capture.[5]

Marsh fought in the vicinity of Shiloh Church on both days of the battle

Following the victory at Fort Donelson, General Ulysses S. Grant was thrust into the public eye and at the same came under attack from department commander Henry W. Halleck. During this time Colonel Marsh and others presented Grant with an ivory-handled sword. Marsh took the occasion to publicly profess his confidence in General Grant and denounced the "jealousy caused by his recent success".[6] He assumed command of the 2nd Brigade when recently promoted Brig. Gen. W.H.L. Wallace took command of the 2nd Division. On the morning of April 6, 1862 messengers managed to alert Colonel Abraham M. Hare of the 1st Brigade that a battle was underway but news of the fighting had not reached Colonel Marsh until a cannonball soared through his brigade's camp.[7] Early in the fighting Marsh's brigade was forced into a disorderly retreat until he and General McClernand managed to rally units of the 1st Division behind Shiloh Church. Marsh then led a counterattack which managed to overrun a Confederate battery but proved costly. Once again Marsh was forced to withdraw his dwindling command. Around 5:00pm he made a final stand supported by remnants of three other brigades.[8] On April 7 he led his brigade in recapturing lost ground in the vicinity of Shiloh Church where he had seen action the day before.

Following the battle of Shiloh Colonel Marsh was transferred to command the 3rd Brigade, 1st Division stationed at Jackson, Mississippi. He was appointed Brigadier General of U.S. Volunteers dated November 29, 1862, though his appointment was later withdrawn. He was transferred to command the 1st Brigade in John A. Logan's 3rd Division of the XVII Corps in the opening stages of Grant's First Vicksburg Campaign. Colonel Marsh resigned on April 22, 1863.[9]