One 'L' sufficient.
Robert B Blackwell of Bedford County TN, paroled a Major and provost Marshal of Buford's Cavalry Brigade. Evidently he had been a civil official in Bedford County. After executing several Federal prisoners, Blackwell and his band found middle Tennessee a bit too dangerous and sought safety south of the Tennessee River. According to personal testimony in Confederate Veteran Magazine, he then killed a Confederate recruiting officer from the 17th Tennessee Regt. A Federal provost marshal gave a pass to Blackwell's wife and two small children, who evidently jpined him in Alabama.
About this time someone named Blackwell who represented himself as a Confederate officer appeared in Shelby County AL. Local history describes his reign of terror in the area now encompassed by Chilton County AL. Within a short time as many as twenty civilians are murdered or executed, most of them soldiers thought to be AWOL or family members assisting deserters. When the war ends Shelby County citizens take vengance on men thought to have been in league with Blackwell. No one is ever charged in connection with any of these killings.
In March 1865 General Forrest assigns Abram Buford to command of Alabama cavalry then operating in Alabama. The 7th Alabama and Russell's 4th Alabama Cavalry go into camp at Montevallo in Shelby County AL. As the only Confederate commands that reported to Buford, these cavalrymen are sent to Greenville to meet a Federal raid from Pensacola FL. Buford's men and survivors of Clanton's Alabama Cavalry then form a picket line in Lowndes County to watch Wilson's command, then bridging the Alabama River at Selma. It is not known whether Blackwell was then with Buford's command or not.
Wilson's Cavalry Corps presses Buford's small force from Benton in Lowndes County east through Montgomery to the Chattahoochee River. After the Confederate defeat at Columbus GA on Easter Sunday, Buford rides west across the state to join Forrest' command at Gainesville AL. Blackwell signs a parole there on May 10, 1865, representing himself as a member of General Buford's staff.
In October 1865 Blackwell and his wife have a child in Arkansas. Shortly thereafter the family moves to Parker County TX. Family trees have a death date in May 1868. The article from Confederate Veteran Magazine strongly suggests that a patient avenger followed him to Parker County. It's noteworthy that two family members from Parker County TX later named sons Robert B Blackwell. I also found someone in Shelby County who named their son born in 1865 "Colonel Blackwell" (don't recall last name).