Gertrude Atherton 
Valiant Runaways [PDF ebook] 

Though originally intended for younger audiences, The Valiant Runaways is a rip-roaring action-adventure tale that will ensnare the interest of readers of all ages. Roldan Castanada is a young man who has strong opinions about everything and who is not inclined to take orders he doesn’t agree with. But when he’s conscripted as a soldier in the conflict between U.S. and Mexico over control of California, Roldan’s attitude begins to change.