Leaving Iowa August 6, 1861, it proceeded to Cape Girardeau, Mo., where it was assigned to Prentiss's Division. It was engaged on active duty in Missouri for several months, during which it fought at Belmont, sustaining the heaviest loss of any regiment in that battle. The first man killed at Belmont was one of the skirmishers of the Seventh; its loss was 51 killed, 127 wounded, 39 captured, and 10 missing; a total of 227 out of 410 engaged. Lieutenant-Colonel Augustus Wentz and three line officers were killed there, while Colonel Lauman and Major Rice were wounded. At Fort Donelson the regiment was in General C. F. Smith's Division, Colonel Lauman commanding the brigade; loss 2 killed and 37 wounded. At Shiloh,--then in Tuttle's Brigade, W. H. Wallace's Division,-- the regiment was on parade for inspection when the army was surprised by the Confederate attack; the Seventh moved promptly to the front, and immediately became engaged; loss, 10 killed, 17 wounded, and 7 missing.

At the battle of Corinth,--October 3d and 4th, 1862--it was in Davies's Division; under command of Colonel Rice it made a stubborn fight, capturing a stand of colors, but losing 21 killed, 87 wounded, and 13 missing; over one-third of those engaged. The year 1863 was spent near Corinth, and in 1864, the regiment having reënlisted, entered upon Sherman's Atlanta campaign, during which it was hotly engaged at Lay's Ferry, Ga. (Resaca), where it lost 11 killed and 51 wounded. It was then in Rice's (1st) Brigade, Sweeny's (2d) Division, Sixteenth Corps. After the fall of Atlanta, it was placed in Rice's (4th) Division. Fifteenth Corps, in which it served during Sherman's Georgia and Carolina campaigns. Mustered out July 12, 1865.