Heinrich (Henry) Phillip Spaeth was born in the Württemberg region of Germany on December 25, 1838, the son of Christopher and Julia Spaeth. Around 1845, the family settled in Cincinnati, Ohio, where Christopher worked as a grocer until his death from cholera in 1849. After his father's passing, Heinrich held jobs at a paper box factory and a furniture factory and subsequently enlisted in Company D of the 9th Ohio Volunteer Infantry, a German-American regiment. Spaeth enrolled as a private in April 1861, and fought in the battles of Mill Springs, Perryville, Chickamauga, Missionary Ridge, and Resaca as part of the Army of the Cumberland. He was discharged as a 1st lieutenant in June 1864, after which he returned for three years to Cincinnati and worked as a clerk. In 1867, he moved to Aurora, Indiana, and opened a hardware store, H.P Spaeth & Co. Around 1870, he married Sophia Kastner, with whom he had two children: Julia, (1871-1960) and Frederick (1873-1950). Sophia died in 1874, and 6 years later, in 1880, Spaeth married Mary E. Smith (b. 1842). Upon the 1911 publication of the book The Truth about Chickamauga by Archibald Gracie, he gathered accounts from fellow soldiers in order to refute Gracie's claims about the role of Van Derveer's brigade at Chickamauga. Spaeth lived until at least 1920.