Are you sure that your "John P. Braden of Montague County" was in Burford's 19th Cavalry?
John P. Broden definitely served in Johnson's 14th TX Cavalry along with Joseph and Absolem Broden who, along with John P., are listed as "Braden" in the Montague County and Wise County militia records. .."J.P. Braden" signed for his paycheck. ..Below are the Braden entries from my 134-page Name Index.
BRODEN, BRADEN, BRIDEN
Absolem D. Broden, b-1834 TN; Johnson's 14th TX Cav, Co F (Lt, Montague Co, TST), A-287, A-288, A-317
Henry, b-1802 GA (Montague Co, TST), A-287
Henry Briden, b-1810 Germany; m-Martha (Johnson Co, TST), A-228
John P. Broden, 1837 MO-c1875; m-Virginia; Johnson's 14th TX Cav, Co F (Montague & Wise Co's, TST), A-288, A-317, A-335
Joseph S. Broden, b-1842 MO; Johnson's 14th TX Cav, Co F (Montague Co, TST), A-288
Late in the War, many who had served in Burford's 19th Cav. and other CSA units protected livestock and settlers of the North and West Frontier. ..And yes, later many were members of the TST militias commanded by Throckmorton, Well's CSA Battalion, McCord's CSA Frontier Rangers, as well as Bourland's CSA Regiment.
Granted my study is ongoing, but the focus of my 1,022, 7.3-pound book was/is to outline the members, organization, and timeline of those soldiers patrolling the North and West Frontier.
P.S. Please send me info. that will help us compile listings of men who patrolled the Frontier that stretched into Colorado, New Mexico, Indian Territory, and Kansas.