Hammill was born in Chicago, Illinois, and raised in Albion, Michigan, the ancestral town of his grandmother and great-grandparents.
His parents were Caleb Wild & Elizabeth (Pine) Hammill.
Hammill married Maude Echols of Fort Smith, Arkansas, in 1903.
Hammill died in Paris, France, on July 19, 1921.
He is interred in Woodland Cemetery in the Bronx, New York.