Organized at Chicago in September, 1862. It was ordered to Memphis, November 9th, in which vicinity it remained until the opening of the Vicksburg campaign, in April, 1863. In the meantime it was engaged of Grant's March through Northern Mississippi, and on the Yazoo Expedition. During the Vicksburg campaign, the regiment served in Boomer's (3d) Brigade, Quinby's Division, Seventeenth Corps.

Its first encounter with the enemy occurred at the battle of Jackson, May 14th, in which it lost 1 killed and 6 wounded. Two days later it fought at Champion's Hill, a hard fought field, where its casualties amounted to 38 killed, 113 wounded, and 11 missing; total, 162. In the assault on Vicksburg, May 22d, it lost 4 killed and 51 wounded; Colonel Boomer, the brigade commander, lost his life in this action. After the surrender of Vicksburg, and the evacuation of Jackson, the division moved to Memphis, where it was transferred to the Fifteenth Corps; thence, to Chattanooga, where it was engaged in the storming of Missionary Ridge. Colonel Putnam fell in this battle, the loss of the regiment being 20 killed, 42 wounded, and 27 missing.

During the Atlanta campaign, the division (General John E. Smith's) guarded the line of communication, the regiment being stationed at Allatoona Pass, where it was engaged in the memorable defense of that place, under General Corse; loss, 21 killed, 52 wounded, and 10 missing. The regiment was commanded in this action by Major James M. Fisher, and numbered 290 men. It was during this fighting that General Sherman signalled the historic message to "Hold the Fort." The Ninety-third afterwards accompanied the Fifteenth Corps on the March to the Sea, and through the Carolinas. The brigade was commanded at Missionary Ridge by General Matthies; at Allatoona, by Colonel Tourtelotte (4th Minnesota); and on the March to the Sea by Colonel McCown,— then the First Brigade, Third Division (Gen. J. E. Smith's), Fifteenth Corps.