In 1860, E. L. Deaton observed that when fighting at night, Comanches used whistles to keep track of each other. Floyd J. Holmes, Indian Fights on the Texas Frontier: A True Account of the Last Exciting Encounters with Redskins in Hamilton, Comanche, Brown, Erath, and Adjoining Counties, as recorded by E. L. Deaton, Fort Worth: Pioneer Publishing Co., 1927.