On Mar. 6, 1863, Secretary of War James Seddon ordered Johnston to take command of the Army of Tennessee, General Bragg being absent to attend to his wife during a serious illness. After her recovery Bragg's instructions were to report to Richmond VA. Unfortunately Johnston's old wound from Seven Pines impaired his health, and he requested relief on April 10, 1863. Rather than going to richmond for further orders, Bragg returned to command of the Army of Tennessee.
Regarding troops captured at Arkansas Post and exchanged to serve east of the Mississippi River, four independent cavalry companies were involved. These included the Texas companies of Alf Johnson and Samuel J. Richardson, and the Louisiana companies of Capts. L. M. Nutt and William B. Denson. Post-exchange service records of the four captains suggest that they served for some time in the Army of Tennessee as independent mounted troops.