Thompson and his brother Jesse were in Dutchess County, New York at the start of the American Revolution, in the precinct of North East.
Promoted to major, Israel Thompson commanded several companies of militia fortifying Red Hook near Peekskill in August–September, 1776.
[3] Later in the Revolution he served as one of the Dutchess County Commissioners of Conspiracies, who were in charge of investigating and arresting Tories and in some cases sending them down-river to British-held New York City.
[9] Thompson's wife's name was Millicent; she was the daughter of Enos Mead, who died about 1774 leaving substantial land claims in Dutchess County to her and his other children.
[10][11] Israel Thompson appears on a mural of the ratification in the United States Post Office (Poughkeepsie, New York), painted as a Works Progress Administration project during the building's construction 1937-9.