Down by the Glenside was sung in the film Rio Grande, the third of John Ford's Cavalry Trilogy. It was sung by a group of troopers -- played by the Sons of the Pioneers with Stan Jones the lead singer --to John Wayne and his estranged wife, Maureen O'Hara, who was visiting the troop because their son had enlisted and had been assigned to his father's command. Maureen O'Hara was not in Fort Apache or She Wore a Yellow Ribbon -- the female leads in those films were, respectively, Shirley Temple and Joanne Dru. And, yes, tough old Irish sergeant Victor McLagan did wipe away a tear as the song was sung. I have all three films on video tapes and have watched each of them probably a dozen times.