Gideon Barnum was a Sergeant in Captain Lawrence's company, Colonel Walbridge's Vermont Regiment during the Revolutionary War. He was on the Orphan List. The surname of his first wife is not known. The US Census of 1790 shows Gideon Barnum, with one additional free white male of 16 years and upwards, one free white male under 16 and five free white females, living in Danby, Rutland County, Vermont. In Democracy in the Connecticut Frontier Town of Kent, there is mention of a Gideon Barnum, as follows: "Gideon Barnum, an original proprietor, settler, and freeman and one of the most active speculators, met his Waterloo in 1761. He had made some sixty speculative transactions, mostly in iron properties, and had served the town [of Kent] as grand juror and highway surveyor. His ironworks may have pulled him down or he may have lost out on the Barnum silver-mine fiasco. He left town, and creditors Jonathan Morgan and John Griffis of Sharon took his dwelling house and 'the bellows that belong to the iron works.' Barnum's tax list rose and fell, reaching 112 Pounds in 1744 and falling to 29 Pounds in 1752."
Gideon and his father Ebenezer were two of the signers of a covenant incorporating them into a church by the neighboring towns of Milford and Sharon, 29 Apr 1741. A list of the members of the new Congregational Church of Kent in that same year included the names of Abigail and Anna Barnum (probably Gideon's wife and daughter).