It does make sense that the "guard" was one of courtesy to protect the men from the likes of Anderson. Even after arming the Union officers (who had been permitted to keep their sidearms, so the arms must have been rifles), Graves and his men would have been outnumbered by Anderson's people.

However, it is easy to believe that the "show of force" would have caused the bandits to withdraw. Cowards often avoid conflict when faced with brave and honorable men. As Lt. Graves is reported to have said; " I command Confederate soldiers...."

Men of Anderson's calibre much preferred easier targets.

J.Y.