The First Wisconsin Infantry (Three months) was organized at Camp Scott, Milwaukee, April 27, 1861, in response to the call of President Lincoln under date of April 14, 1861, for seventy-five thousand men. The First left the state on the 9th day of June, proceeding under orders to Harrisburg, PA, soon thereafter was transferred to Hagerstown, MD, and assigned to the division of the Union Army commanded by Major General Patterson. In the advance of Martinsburg, VA (present-day West Virginia), it participated in the Battle of Falling Waters July 2, 1861, losing one man killed and five wounded and one prisoner. The term of service for which the men enlisted having expired, the First returned to Camp Scott, Milwaukee, and was mustered out of the military service of United States on August 21, 1861.
A week after the muster out of the First Wisconsin Infantry (three months) orders were received to reorganize the regiment for a term of enlistment for three years. This work proceeded rapidly under the supervision of Col. John C. Starkweather at Camp Scott, Milwaukee and on the 19th of October, 1861, the First was mustered into the service of the United States.
On the 28th of October the regiment left the state under orders to report at Louisville, KY. Thereafter, and for the full period of its service, the First was actively engaged in the several campaigns in and across Middle Kentucky and Tennessee and Northern Georgia, including the Atlanta Campaign of 1864 under General William T. Sherman. During 1862 the command to which the First was assigned took part in several minor engagements and long marches and took part in the battles of Perryville or Chaplin Hills, KY, October 8, 1862; Stone's River or Murfreesboro, TN, December 30-31, 1862 and January 1, 1863. The Tullahoma Campaign as a part of the army of the Cumberland, Gen. Rosecrans commanding, June 23-July 7, 1863. Was actively engaged in the battle of Chickamauga, GA, September 19-20, 1863; at Missionary Ridge, TN, November 25, 1863. On the 2nd of May, 1864, the First joined Sherman's Army in the advance on Atlanta, as a part of the Third Brigade First Division, Fourteenth Army Corps, Army of the Cumberland, and with this command participated in Northern Georgia in the battles of Rocky Face Ridge, May 8-11, 1864; Resaca, May 14-15, 1864; Dallas, May 26-June 1, 1864; Chattahoochie, July 5-17, 1864; Peach Tree Creek, July 20, 1864; Atlanta, July 22, 1864, and Jonesborough, August 31-September 1, 1864.
The term of service of the regiment being about to expire, on the 16th of September 1864 orders were received from the War Department to transfer the veterans who had re-enlisted and those recruits whose term of service had not expired to the Twenty-first Infantry. This transfer of 368 men was completed and on the 21st of September the regiment left for Nashville, TN where they encamped until the 6th of October, when they left for Milwaukee and were disbanded at Camp Washburn, October 21, 1864.