Edward Sinnott "Tex" O'Reilly was an American soldier of fortune, writer, journalist, and film actor. He is said to have fought in ten wars under many flags. Initially serving in the U.S. Army in the Spanish–American War, the Philippine–American War, and the Boxer Rebellion, he would claim to fight in several conflicts in Central America and to have fought with Pancho Villa in Mexico and claimed to have fought in the Rif War with the Spanish Foreign Legion in North Africa. He worked as a reporter for the Associated Press. He wrote an autobiography, Roving and Fighting, and Lowell Thomas wrote Born to Raise Hell about him. The latter book has been reprinted and is distributed by The Long Riders' Guild Press. He was the author of Pecos Bill.

Francisco "Pancho" Villa was a Mexican revolutionary and general in the Mexican Revolution. He was a key figure in the revolutionary movement that forced out President Porfirio Díaz and brought Francisco I. Madero to power in 1911. When Madero was ousted by a coup led by General Victoriano Huerta in February 1913, Villa joined the anti-Huerta forces in the Constitutionalist Army led by Venustiano Carranza. After the defeat and exile of Huerta in July 1914, Villa broke with Carranza. Villa dominated the meeting of revolutionary generals that excluded Carranza and helped create a coalition government. Emiliano Zapata and Villa became formal allies in this period. Like Zapata, Villa was strongly in favor of land reform, but did not implement it when he had power. At the height of his power and popularity in late 1914 and early 1915, the U.S. considered recognizing Villa as Mexico's legitimate authority.