Career
Hamilton served in the United States Army. He was stationed in the United States Army Quartermaster Corps along the Mexican border from 1913 to 1914. He also served with General John Jay Pershing during Pershing’s expedition into Mexico during 1915 and 1916.
Hamilton became interested in Mexican postage stamps and postal history while serving in Mexico.
While in Mexico, he obtained first hand information on Mexican postage stamp issues, and became an expert on stamps of Sonora and those that were issued by various postal authorities during the Mexican Revolution. The colonel’s Mexican collections were considered world class, and he exhibited portions of the collections at shows and exhibitions.
Hamilton wrote extensively of his studies of Mexican stamps, particularly those of the Mexican Civil War era.