"There was a brave old Texan, his name was Mustang Gray." When the Mexicans invaded Texas, he was taken prisoner. "He wore the yoke of bondage through the streets of Monteray. A senorita loved him...." and turned him loose
Thorp/Fife notes that this song takes two forms: "In Hewitt's original aria interest is focused on the senorita and her heroic deed. The texts most current in Western American oral tradition... bring the American soldier-cowboy into central focus...."
The piece seems to have drawn its title from the 1847 novel _The Volunteer, or The Maid of Monterrey_, by Ned Bluntine.
The song has been variously credited to John Hill Hewitt, Tom Grey, and James Lytle. Thorp/Fife considers Hewitt (a well-known composer) to be the most likely candidate.
As "Mustang Gray," this song is item dB28 in Laws's Appendix II. - RBW