After the Confederates abandoned Corinth in the summer of 1862, the 1st Missouri was transferred to the Vicksburg, Mississippi, area. The regiment, as well as the rest of Bowen's brigade, was expected to be part of the Confederate assault at the Battle of Baton Rouge, but arrived too late for the fighting. By early October, the 1st Missouri was part of Major General Earl van Dorn's Army of West Tennessee. The regiment was part of Bowen's brigade of Major General Mansfield Lovell's division. Bowen's brigade also contained the 6th Mississippi Infantry, 15th Mississippi Infantry, 22nd Mississippi Infantry, Caruther's Mississippi Battalion, and Watson's Louisiana Battery. On October 3, at the Second Battle of Corinth, the 1st Missouri was part of the Confederate assault on the Union's outer defensive works. The 1st Missouri, along with the 33rd Mississippi Infantry, broke the line of the 15th Michigan Infantry, contributing to the collapse of the initial Union line. During the fighting, the 1st Missouri became separated from the rest of Bowen's brigade, and fought with the brigade of Brigadier General John C. Moore for the rest of the day. The 1st Missouri outflanked a Union position commanded by Brigadier General John McArthur, helping Moore's brigade break the line. Moore's brigade then ran against Union reinforcements commanded by Colonel Marcellus Crocker. The 1st Missouri outflanked the 15th Iowa Infantry, which, accompanied by Moore's primary assault on Crocker's line, led to the collapse of the Union position. However, Moore's brigade was not reinforced, and the Confederate assault died down. The next day, Bowen's brigade was only briefly engaged during Confederate attacks on the stronger interior Union position, as Lovell's division was mostly inactive on October 4.