John Densmore was born in Darlington, Ontario on November 8, 1839. He is the son of John and Clarissa (Blake) Densmore. John married Sarah Reynolds in Canada on June 18, 1856. Between 1859 and 1861, John and his family came to the United States and settled in rural St Clair County near, Smith’s Creek, Michigan. John served in the Civil War in the Michigan 11th Infantry, Company K. He enlisted as a Private on February 25, 1865 at the age of 26 in Jackson, Michigan. His ocupation was listed as Farmer on his enlistment papers. He mustered out on Septemeber 16, 1865 in Nashville, Tennessee.
He would after the War work for a time as a ship carpenter. John died in Smith's Creek, Michigan and was buried in Smith's Cemetery. Eventually his remains were moved to Woodlawn Cemetery to be buried next to his wife Sarah L. Densmore.