On October 21, 1861, Simms was appointed to the temporary rank of colonel in the Confederate States Army. He was appointed lieutenant colonel in the Provisional Army of the Confederate States on December 24, 1861, and was assigned to the First Battalion, Kentucky Cavalry.
Simms received a temporary rank of colonel in the Confederate States Army on October 21, 1861. He was later appointed as lieutenant colonel in the Provisional Army of the Confederate States on December 24, 1861, and became part of the First Battalion, Kentucky Cavalry.