Organization 

The Twentieth Wisconsin Infantry Regiment (20th Wisconsin Infantry Regiment) organized at Camp Randall, Madison, Wisconsin. Their final muster into the service of the United States completed on August 23, 1862.  The regiment left the state on August 30 for Missouri.

Active Duty 

To start, they joined General Herron’s Brigade at Rollo, MO, on September 6. Then, they marched to southwestern Missouri. In Missouri, they participated in the campaign being conducted against the Confederates by the Army of the Frontier in southwestern Missouri and northwestern Arkansas.  Also, they took part in the battle of Prairie Grove, AR, on December 7, 1862. 

Then, the Twentieth continued in active service in southwestern Missouri until June. At that time, they transferred to Vicksburg and took their place in the trenches on June 15, 1863. They would remain a part of the besieging forces until the surrender on July 4. After Vicksburg, the regiment took part in various expeditions in Mississippi and Louisiana, including one to Natchez, Port Hudson, and Morganza.   

Later in the year, the Twentieth accompanied the Texas expedition which left New Orleans on October 26, 1863. They disembarked at Brazos, Santiago, TX, going on duty at or near Brownsville, TX, on the Rio Grande, where they remained until the following August.  During this time, they participated in many expeditions, including a two-day excursion across the Rio Grande into Mexico, from January 12 to 14, 1864.  

Returning to New Orleans in August, the Twentieth formed a portion of the land forces accompanying Admiral Farragut’s Expedition against the Confederate forces in Mobile Bay in August 1864. The regiment participated with the land forces investing Ft. Morgan until the surrender of that stronghold on August 23, 1864. 

Thereafter, with the Union forces in southern Alabama, they took part in the investment of Spanish Fort from March 27 to April 8, 1865. They also participated in the reduction and capture of Fort Blakely on April 9, 1865. In late June, the Twentieth situated at Galveston, TX, where they remained and performed the usual duties of garrison service. They continued until mustered out of the service of the United States on July 15, 1865.  Later, they reached Madison on July 30, and was disbanded on August 9, 1865. 

Casualties  

The Twentieth Wisconsin Infantry Regiment lost 5 officers and 100 men to mortal wounds, along with an additional officer and 145 men to disease. 

For Further Research

Search our collections for photos and artifacts from Wisconsin in the Civil War. Read about other Wisconsin Civil War regiments. For detailed regimental histories of the U.S. Civil War, consult the Frederick H. Dyer, Compendium of the War of the Rebellion: Regimental Histories.

The histories above, unless otherwise noted, are adopted from Charles E. Estabrook, ed., Records and Sketches of Military Organizations, (Madison, 1914).