After organizing, the regiment was designated the 5th Missouri Infantry Regiment despite the 6th Missouri Infantry Regiment having formed first. After joining the First Missouri Brigade, the regiment saw light action at the Battle of Iuka on September 19, 1862, where it suffered five casualties. The regiment was next engaged at the Second Battle of Corinth on October 3rd and 4th. At Second Corinth, the regiment was in Colonel Elijah Gates' brigade of Brigadier General Louis Hébert's division of the Confederate Army of West Tennessee. On the first day at Corinth, Gates' brigade entered the action around 4:45 p.m., when it moved to aid Brigadier General Martin E. Green's brigade. However, Green ordered a charge after only one of Gates' regiments, the 2nd Missouri Infantry Regiment, had fully deployed. The Confederate charge broke the Union outer line, but Price decided not to attack the interior Union lines on the night of the 3rd, instead choosing to wait for the next morning.