The Eleventh Wisconsin Infantry Regiment was organized at Camp Randall, Madison, WI, and mustered into the service of the United States on October 16, 1861. It left the state on the 20th of November, proceeding directly to St. Louis, where it was at once assigned to service patrolling and guarding railways. The regiment continued in this line of duty until March 1862, when with other Union forces it participated in a number of expeditions into Northern Arkansas and Southern Missouri and took part in the actions at Bayou Cache, AR, July 7, 1862.
The winter of 1862-1863 was spent in Southern Missouri, occupied principally in patrol duty and guarding railways and other lines of communication. On the 11th of March, 1863, the Eleventh moved to Memphis, TN, and then down the Mississippi River to Milliken's Bend, LA, occupying different positions. As a part of Grant's forces the regiment crossed to the east side of the Mississippi below Vicksburg on April 30, and moved forward at once and took part in the battle at Port Gibson, MS, on the 1st day of May, 1863. It was next engaged in the battles of Champion's Hill, May 16, and Black River Bridge, MS, May 17, 1863, and took part in the siege of Vicksburg which followed May 19 to July 4, 1863. After the surrender of Vicksburg the Eleventh participated in the Jackson Campaign, MS, July 5-25, 1863. In August it proceeded to Southern Louisiana and was assigned to the Thirteenth Army Corps and participated with this organization in the operations in the Teche Country, LA, October 3 to November 30, 1863. In the latter part of November the Eleventh was a part of the force engaged in an expedition to Brazos Santiago, TX, about six hundred miles west of New Orleans.
Returning to Brashear City (now Morgan City, LA), the Regiment continued in active service until February 26, 1865, when it was assigned to the force sent to capture Mobile, AL. Here the Eleventh participated in the siege of Spanish Fort, March 26 to April 8, 1865, the assault and capture of Ft. Blakely April 9, 1865, and the occupation of Mobile, April 12. During the summer following the Eleventh was engaged in guard duty in Southern Alabama. It was mustered out of service on the 4th of September and proceeded to Madison and was disbanded September 28, 1865.