Career
He was among the 34 men received the Medal of Honor for "bravery in scouts and actions" during several engagements against the Apache Indians in the Arizona Territory between August and October 1868. John O'Callaghan was 1838, born in New York City, New York, United States. O'Callaghan later moved to San Francisco, California.
While living in San Francisco, O'Callaghan enlisted in the United States Army. Assigned to frontier duty with B Company of the Eighth United States Cavalry regiment, O'Callaghan participated in campaigns against the Apache Indians in the Arizona Territory during the late 1860s and eventually rose through the non-commissioned ranks, gaining promotion to the rank of sergeant. Between August and October 1868, O'Callaghan was involved in several engagements with the Apache and was cited for "bravery in scouts and actions against Indians".
