Wheeler's mother died while he was just a youth, and his father placed the boy with a family on Long Island, New York while he continued his recruiting and intelligence activities for the British during the American Revolution. After the War Wheeler married, and lived in New York City until about 1800. He then appears to have lived at Ringwood, north of Toronto, until 1808. On 16 Mar 1809, Wheeler Barnum, tailor, purchased 105 acres of land in the north parts of Lot 7 and 8, Concession 1, Charlotteville Township from his brother Nathan Bunnell Barnum, Jr. In the 1808 Assessment, he had a valuation of under £100 and his tax came to six days work on the roads. In the 1809 Assessment, he had 202 acres uncultivated and 8 acres cultivated and lived in a log cabin, all valued at £43. In 1810, Wheeler had a tax of 6 days of work on the roads. The 1811 valuation showed him at 194 acres uncultivated and 16 acres cultivated. His livestock included 2 oxen, 2 milch cows and 1 horned cow. During the War of 1812, Wheeler served as a private in the 1st Regiment of Norfolk Militia and died of disease while on duty. Martha Barnum, widow of Wheeler Barnum was awarded £20; her husband had died of fatigue on an expedition to the westward March, 1813. Martha Barnum his widow received a Militia pension and held a Tavern license in 1818. His widow Martha received a pension of £75.18.10.5 for the period from his death to 31 Dec 1816. She received a further £20 for 1817. Wheeler's widow continued at Charlotteville Township and in 1815 had an assessment of £54, her tax 4 days of work on the roads. She may have been living with Wheeler's brother Nathan, which would account for the lower valuation for her and a marked increase in Nathan's for that year. Martha apparently had a dispute with her neighbor Joseph Wood. On 9 Oct 1816, Joseph Wood, Christian Baker and Henry Willis came before the Court of the Quarter Sessions and ordered to place a bond for "the peace and Good Behavior of Joseph Wood towards all his Majesty's liege subjects and particularly towards Martha Barnum. On 26 Dec 1818, the Court took into consideration Tavern Bills and agreed as follows -- Martha Barnum £6.
He died as a result of an illness contracted while serving as a soldier during the War of 1812.