Jacob Ammen was a college professor, civil engineer, and a general in the Union Army during the American Civil War.

Within a week after the Confederate bombardment of Fort Sumter in April 1861, Ammen rejoined the Federal army, serving as a captain in the newly raised 12th Ohio Infantry. He was soon commissioned as colonel of the 24th Ohio Infantry. After training at Camp Chase, Ammen’s regiment was sent in late July to serve in western Virginia, seeing their first combat at the Battle of Cheat Mountain.

Shipped to the Western Theater, Ammen led a brigade in the Army of the Ohio at the Battle of Shiloh and the Siege of Corinth. Ammen was promoted to brigadier general on July 16, 1862. In August, Ammen assumed the division command vacated by William “Bull” Nelson, who had been given a new command and sent to defend Richmond, Kentucky.

When his health deteriorated, Ammen then performed administrative duty for nearly a year, commanding Camp Douglas in Illinois in early 1863, as well as other Federal garrisons. In late 1863, he returned to the field and commanded the Fourth Division of the XXIII Corps. In September 1864, his 800-man force blocked the vital Virginia and Tennessee Railroad at Bull’s Gap, Tennessee, during Stephen G. Burbridge’s Saltville raid. Shortly before the end of the war, he resigned in January 1865 and returned home.