Post-war, only two Confederates were tried, convicted and executed - Henry Wirz (Andersonville) and Champ Ferguson (guerrilla). All other possible military tribunals were ceased by proclamation of President Andrew Johnson in 1866.
The revolver in his shoulder holster had Mother of Pearl grips. For a gunfighter, MOP is not a good choice. MOP is made of sea shell and will break easily if struck. Furthermore, with a sweaty palm they are very slippery. It is doubtful a lawman would have MOP on weapons he would stake his life on.
Jeff Fahey opening lines are reminiscent of Brian Dennehy lines as Cobb in Silverado 1985.