The Eighty-third Infantry was organized at Monmouth in August, 1862, by Colonel A.C. Harding, and was mustered into the United States'  service August 21.

Companies A, B, C, F and H were recruited in Warren County; D, in Mercer: E. G. I. And K, in Knox.  The Regiment moved from camp August 25, via Burlington and St. Louis to Cairo, arriving there the 20th, and reporting to Brigadier General Tuttle, commanding post.  September 3, moved to Fort Henry.  On the 5th moved to Fort Donelson, leaving two companies at Fort Helman and three at Fort Henry.  The Regiment remained at Fort Donelson during the year.  Colonel W. W. Lowe, Fifth Iowa Cavalry, commanding Brigade.

The companies at Forts Henry and Helman subsequently rejoined the Regiment and it remained at Fort Donelson until September 20, 1863, when the right wing moved to Clarksville.  The Regiment had heavy guard duty to perform and as the whole country, especially the banks of the Tennessee and Cumberland Rivers, were infested with guerrillas, we had daily skirmishes with the enemy.  Some of them were quite severe, as at Waverly, Tenn., and at Garretsburg, Ky., where the lamented General Ranson, then Colonel of the Eleventh Illinois, had command.

On the 3rd of February, 1863, at Fort Donelson, nine companies of the Eighty-third, with Company C, Second Illinois Light Artillery, successfully resisted the attack of Forrest and Wheeler with 8,000 men.  The battle lasted from 1:30 until 8:30 o'clock P.M., when the enemy was compelled to retire with a loss of 800 killed and wounded. The loss of the Regiment was 13 killed and 51 wounded.  Colonel Harding was promoted to Brigadier General for gallant conduct on this occasion and Lieutenant Colonel A. A. Smith to Colonel.  Among the killed were Captain P. E. Reed, Company A, Lieutenant Harmon D. Bissell, Quartermaster of the Regiment, and First Sergeant James Campbell, Company C.  Among the wounded was Captain John McClanahan, of Company B, who while in the act of changing position to meet an attack, was wounded with a minnie ball, from the effects of which he died February 23.

On the morning of the 20th of August, 1864, Captain William M. Turnbull, of Company B, with eleven of his company, left Fort Donelson in pursuit of a party of five guerrillas, who were making their way to the Tennessee River with a lot of horses, but failing to overtake them he was overpowered while returning to his command by a party of guerrillas secreted in the timber, and he and seven of  his men were killed, while one had both his legs broken, but he was afterward cowardly murdered by guerrillas, who found him lying helpless in a barn where some humane citizen had taken him for safety.  But three of the party escaped to tell the sad fate of their companions.

While at Clarksville the Regiment was engaged in several expeditions under Major General L. H. Rousseau in pursuit of Forrest and Wheeler, who were attempting the destruction of General Sherman's communications.

During the year 1864, the Regiment had some two hundred miles of communications to guard and much heavy patrol duty.  During the winter of 1864-'65, the Eighty-third was on provost duty at Nashville, Tenn.

Before the muster out of the Regiment, the following order was received by Colonel Smith commanding.

HEADQUARTERS DISTRICT OF MIDDLE TENNESSEE
Nashville, Tenn., May 31, 1865

Colonel A. A. Smith, Commanding Fifth Sub. District Middle Tennessee.

Dear Colonel - By an order just received the troops of 1862 will be mustered out of services.  Your Regiment will go out under that order.  I am unwilling to part with you and your officers and men without expressing my highest commendation of the soldierly bearing and gentlemanly conduct of all during the time they have been under my command.  At the time when I most needed brave men and steady soldiers to drive Wheeler and Forrest out of the district I was but too happy to avail myself of the services of as many of your Regiment as could be spared for that duty.  And relying greatly upon them I was not disappointed in their deportment.

I have not been troubled with complaints against them for disorderly conduct and marauding, but their deportment in the army and community has been brave and soldierly, proving that the brave man and true soldier is always honest and just.  I can truly say I do not know a regiment in the service whose brave and soldierly bearing more fully entitles it to the respect and gratitude of the country than the Eighty-third Infantry, and you and they will take with you, individually and collectively, my sincere thanks for your efficient services and my kindest wishes for your future welfare in all things.

I am, Colonel, very truly, etc. 
               Lovel H. Rosseau. 
     Major General Commanding

On the 26th of June the Regiment was mustered out at Nashville and moved to Chicago, Brevet Brigadier General Arthur A. Smith commanding, where it received final pay and discharge July 4 1865.