At 10:59 a.m. on Nov. 11, 1918, a German machine gun crew fired a burst of rounds at approaching Americans. One bullet struck 23-year-old Pvt. Henry Gunther in the left temple. He died instantly.

While millions of Americans can name Western Front battles like Belleau Wood or the Meuse-Argonne, almost no one remembers the 332nd Infantry Regiment. These Ohio doughboys were the only American ...