John McDouall Johnston was born in Sault Ste. Marie, Michigan, on October 12, 1816, the son of John Johnston (1762-1827) and his wife, an Ojibwa woman baptized as "Susan." He had at least four siblings: Eliza, Charlotte, Anna, and William. After briefly attending the Lowville Academy in New York as a teenager, Johnston returned to Sault Ste. Marie, where he became an interpreter of Native American languages. He served as a translator for Henry Schoolcraft and Major W. V. Cobbs, and on official military projects. Johnston also served as the United States farmer at the Indian agency at Grand Traverse Bay, as Chippewa County inspector of fish, and as a notary public. He received a quartermaster's commission in the Michigan State Militia's 16th Regiment in 1843, and eventually rose to the rank of major. He married Justine Piquette (1816-1913) in 1842, and had nine children: Spencer, Anna, Charlotte, Eliza, James, Antony, Howard, Henry, and William. John M. Johnston died on February 14, 1895.