Their Horses Climbed TreesThe little known story of the 500 volunteers from California who fought in the East during the Civil War years. Their Horses Climbed Trees tells the little known story of the five hundred volunteers from California known as the "California Hundred and Battalion", who fought in the East during the Civil War years, as a part of the Second Massachusetts Volunteer Cavalry Regiment. They served from 1862, when they departed from San Francisco, to the war's