George Gordon Belt was born on September 25, 1825 in Beltsville, Maryland. A dedicated southern sympathizer, in early 1864 Belt used his ranch on the Merced to organize a group of partisan rangers including John Mason and "Jim Henry" and sent them out to recruit more men and pillage the property of Union men in the countryside. For the next two years the Mason Henry Gang, as they became known, posed as Confederate partisan rangers but acted as outlaws, committing robberies, thefts and murders in the southern San Joaquin Valley, Santa Cruz County, Monterey County, Santa Clara County, and in counties of Southern California.
On April 7, 1848, George G. Belt married Bebiana Asorca and they had nine children by 1869. On June 3, 1869, Judge Belt was shot and killed in Stockton by William Dennis over a dispute between them.