The 12th Missouri Infantry Regiment was an infantry regiment that served in the Union Army during the American Civil War. The regiment was organized by Colonel Peter J. Osterhaus, a veteran of the respected 2nd Missouri Volunteer Infantry (3 months, 1861). The majority of the soldiers in the 12th were ethnic Germans. This intermixed German-American unit also had a large portion of its ranks filled by volunteers from Illinois.
Organized at St. Louis, Missouri, August 1861.<br> Attached to Fremont's Army of the West to January 1862.<br> 2nd Brigade, Army of Southwest Missouri, to February 1862.<br> 2nd Brigade, 1st Division, Army of Southwest Missouri, to May 1862.<br> 3rd Division, Army of Southwest Missouri, to July 1862.<br> District of Eastern Arkansas, Dept. of Missouri, to December 1862.<br> 1st Brigade, 11th Division, Right Wing 13th Army Corps (Old), Dept. of the Tennessee, to December 1862.<br> 2nd Brigade, 4th Division, Sherman's Yazoo Expedition, to January 1863.<br> 2nd Brigade, 1st Division, to September 1863.<br> 1st Brigade, 1st Division, 15th Army Corps, to December 1863.<br> 3rd Brigade, 1st Division, 15th Army Corps, to November 1864.
Fremont's advance on Springfield, Missouri, September to November 1861. Moved to Jefferson City, thence to Sedalia and Springfield.<br> To Wilson's Creek October 6âÂÂ8. Duty at Rolla until January, 1862<br> Expedition to Danville December 26, 1861.<br> Curtis' Campaign in Missouri and Arkansas against Price January to March 1862.<br> Advance on Springfield February 2âÂÂ16.<br> Pursuit of Price into Arkansas February 14âÂÂ29.<br> Battles of Pea Ridge, Arkansas, March 6âÂÂ8.<br> March to Batesville April 5-May 3; thence to Helena, Arkansas, May 25-July 14.<br> Expedition from Helena to mouth of White River August 5âÂÂ8.<br> Moved to Ironton-Pilot Knob, Missouri, September 1.<br> To St. Genevieve November 12, and return to Helena November 23.<br> Sherman's Yazoo Expedition December 22, 1862, to January 3, 1863.<br> Chickasaw Bayou December 26âÂÂ28.<br> Chickasaw Bluff December 29.<br> Expedition to Arkansas Post, Arkansas, January 3âÂÂ10, 1863.<br> Assault and capture of Fort Hindman, Arkansas Post, January 10âÂÂ11.<br> Moved to Young's Point, La., January 17âÂÂ23. Duty there until March and at Milliken's Bend until April.<br> Expedition to Greenville, Black Bayou and Deer Creek April 2âÂÂ14.<br> Demonstration on Haines and Drumgould's Bluffs April 29-May 2.<br> Moved to join army in rear of Vicksburg, Mississippi, via Richmond and Grand Gulf May 2âÂÂ14.<br> Mississippi Springs May 12âÂÂ13.<br> Jackson May 14. Siege of Vicksburg, Mississippi, May 18-July 4.<br> Assaults on Vicksburg May 19 and 22. Advance on Jackson, Mississippi, July 4âÂÂ10.<br> Siege of Jackson July 10âÂÂ17.<br> Bolton's Depot July 16.<br> Brier Creek, near Canton, July 17, Clinton July 18.<br> Camp at Big Black until September 27.<br> Moved to Memphis, Tennessee, thence march to Chattanooga, Tennessee, September 27-November 21.<br> Operations on Memphis & Charleston Railroad in Alabama October 20âÂÂ29.<br> Cherokee Station October 21 and 29.<br> Cane Creek October 26. Tuscumbia October 26âÂÂ27.<br> Battles of Chattanooga November 23âÂÂ27.<br> Lookout Mountain November 23âÂÂ24.<br> Mission Ridge November 25.<br> Ringgold Gap, Taylor's Ridge, November 27.<br> March to relief of Knoxville, November 28-December 8.<br> Garrison duty in Alabama at Woodville and Scottsboro, Alabama, and at Cleveland, Tennessee, to May 1864.<br> Atlanta (Georgia) Campaign May 1 to September 8.<br> Demonstration on Resaca May 8âÂÂ13.<br> Battle of Resaca May 13âÂÂ15.<br> Advance on Dallas May 18âÂÂ25.<br> Battles about Dallas, New Hope Church and Allatoona Hills May 25-June 5.<br> Operations about Marietta and against Kenesaw Mountain June 10-July 2.<br> Bushy Mountain June 15âÂÂ17.<br> Assault on Kenesaw June 27.<br> Nickajack Creek July 2âÂÂ5.<br> Chattahoochie River July 6âÂÂ17.<br> Battle of Atlanta July 22.<br> Siege of Atlanta July 22-August 25.<br> Ezra Chapel, Hood's 2nd Sortie, July 28.<br> Flank movement on Jonesboro August 25âÂÂ30.<br> Lovejoy Station September 2âÂÂ6.<br> Pursuit of Hood into Alabama October 1âÂÂ21.<br> Mustered out by Companies from August 12 to November 14, 1864.<br> Consolidated with Detachments from 3rd and 17th Missouri Volunteer Infantry and subsequently transferred to 15th Missouri Infantry.
The regiment lost during service 10 officers and 102 enlisted men killed and mortally wounded and 2 officers and 94 enlisted men by disease. Total 208.