The 12th Missouri Infantry Regiment was an infantry regiment that served in the Confederate States Army during the American Civil War. After mustering into Confederate service on October 22, 1862, as White's Missouri Infantry, the regiment, as Ponder's Missouri Infantry, fought in the Battle of Prairie Grove on December 7, where it charged the Union lines several times. On May 3, 1863, the regiment was named the 9th Missouri Infantry Regiment, and fought under that name until December 15, 1863, when it was renamed the 12th Missouri Infantry Regiment. On July 4, 1863, the regiment, as part of Brigadier General Mosby M. Parsons' brigade, broke through the Union lines at the Battle of Helena. However, Parsons' flanks were exposed, and the Confederates were driven from the field, suffering heavy losses. After Helena, only 168 men remained in the regiment. On November 22, 1863, the survivors of the regiment were combined into two companies, which were then attached to the 10th Missouri Infantry Regiment, although the 12th Missouri Infantry was still treated as a separate unit for reporting purposes. In April 1864, the 12th Missouri Infantry fought at the battles of Pleasant Hill and Jenkins' Ferry. On September 29, 1864, the survivors of the 12th Missouri Infantry were officially merged into the 10th Missouri Infantry, ending the 12th's separate service career.