@danny
Yeah, so basically, at Murfreesboro, P.R. Cleburne's division had consisted of the brigades under the commands of Lucius Polk, St. John R. Liddell, Bushrod Johnson and S.A.M. Wood.
The men in Churchill's command were ordered to the Army in May, just as the main body of Breckinridge's and McCown's divisions were transferred out of the Army of Tennessee to Mississippi. A.P. Stewart, who had been commanding a brigade in B.F. Cheatham's division, had been temporarily commanding McCown's division at the time due to McCown's ongoing court-martial, but would remain with the Army when the division was transferred to Mississippi. He would assume command of the newly formed division, consisting of kind of a hodge-lodge Alabama brigade made up of one veteran Alabama regiment and two largely raw regiments which had been transferred up from the Mobile defenses (Henry Clayton's brigade), another kind of hodge-podge brigade which had been formed under the command of William Bate (the composition of which would change in May), the brigade from Breckinridge's division which had been left with the Army and Bushrod Johnson's brigade, which was transferred into the division from Cleburne's division.
Churchill's brigade would essentially replace Johnson's brigade.
Later, at Chattanooga, Bushrod Johnson's brigade from Stewart's division and St. John R. Liddell's brigade from Cleburne's division would be moved out and would serve as foundational components in two new divisions, which would be commanded by each man, Johnson and Liddell, respectively.
That left three brigades in Cleburne's Division, those under the commands of Lucius Polk, S.A.M. Wood and Thomas Churchill, until Churchill was transferred out of the Army in August (but the brigade retained), with the brigade devolving to the command of James Deshler. Hence, during the Chickamauga campaign, Cleburne's division would consist of the brigades of Polk, Wood and Deshler.
Deshler would be killed on September 20th at Chickamauga.