Born in Hamilton, Ohio, November 29, 1806. In 1828 he removed to Michigan with his parents and there two years later married Amy Kinney Townsend, of the New York Townsends. In Michigan he was successively justice of the peace, and for four years elected associate judge of the circuit court for Cass County. Removing to Iowa in 1839, he was one of the early commissioners of this county, was county assessor under the old law, and was commissioned by Gov. Stephen Hempsted to select the lands in the great 500,000 acre grant of the Federal government to Iowa. He was next a representative in the legislature and was the last county judge of this county, being the incumbent of that office when its duties were enlarged and its title changed to Auditor. He served acceptably as auditor under the new law and was subsequently several times elected justice. Judge Cavanagh was actively and creditably identified with Johnson County.