[1] By the time the 39th was involved in the Siege of Petersburg, Virginia, Allen was a corporal in Company K. When the regiment (as part of the XXIV Corps under Major General John Gibbon) was assaulting Fort Gregg on April 2, 1865, under heavy fire, he was at the front as a color bearer.

At the surrender ceremony at Appomattox Courthouse a week later, Allen was given the honor of carrying Illinois' flag.

He later traveled to Washington, D.C., with General Gibbon and 76 captured Confederate colors.

He received his medal there from Secretary of War Edwin Stanton.

Citation: Gallantry as color bearer in the assault on Fort Gregg.