Edward Cahill was born in Kalamazoo, Michigan, on August 3, 1843, the son of Abraham Cahill, a tanner, and Frances Marsh Cahill. The family lived on a farm near Holland, Michigan, in the 1850s, and returned to Kalamazoo after Abraham's death in 1854. Edward took preparatory classes at Kalamazoo College and worked as a messenger for the state legislature before enlisting as a private in the 89th Illinois Infantry Regiment in 1862. Though he was discharged for disability in December 1862, he began to raise a company for the 1st Michigan Colored Infantry Regiment (later the 102nd United States Colored Infantry Regiment) in October 1863. He served as the unit's captain and in an administrative capacity, approving postwar contracts made between freedmen and their former owners in South Carolina. After his final discharge, Cahill returned to St. Johns, Michigan. He studied law and in 1871 moved to Chicago, where he spent two years as a lawyer. In 1873, he moved to Lansing, Michigan, where he had a long legal career, which included a partial term on the Michigan Supreme Court in 1890. He married Lucy C. Crawford in 1867 and they had two daughters, Clara Bell and Margaret. Edward Cahill died in 1922.