Peter Joseph Osterhaus
Peter Joseph Osterhaus (January 4, 1823 – January 2, 1917) was a German-born American who became a Union Army general in the Civil War and later a diplomat.
He was born in Koblenz, Prussia, and trained at the Berlin Military Academy. After the Revolutions of 1848, he moved to the United States in 1858 and settled in St. Louis, Missouri.
When the Civil War began, Osterhaus became a major in the 2nd Missouri Infantry. He fought in Missouri and Arkansas, including Wilson’s Creek and Pea Ridge, where his troops first contacted the Confederates on the Union left. He was promoted to brigadier general on June 9, 1862.
In 1863 he commanded a division at Port Gibson and later fought in the Vicksburg Campaign, including Champion Hill and the Big Black River Bridge. His division helped with the early attacks on Vicksburg and supported the siege around the city, while protecting the rear during operations toward Jackson.
After Vicksburg, he moved to Tennessee and helped capture Lookout Mountain in the Chattanooga campaign. He then took part in the Atlanta Campaign; a sickness kept him away from the crucial Battle of Atlanta, but he returned to lead at the Battle of Jonesborough. After Atlanta fell, he commanded the XV Corps in Sherman’s March to the Sea.
In March 1865 he became chief of staff for the Military Division of West Mississippi under Maj. Gen. Edward Canby and fought at Spanish Fort and Fort Blakeley. He signed the surrender documents for the Trans-Mississippi forces on Canby’s behalf and left the Army in January 1866.
That year he became U.S. Consul at Lyon, France, but he later settled in Duisburg, Germany. He retired in 1905 and was one of the oldest Army pensioners by 1915. Osterhaus died in Duisburg on January 2, 1917, aged 93, and was buried in Koblenz, Germany. For many years the exact grave site was unclear, and a marker was placed at the old Koblenz cemetery in 2012.
This page was last edited on 2 February 2026, at 05:10 (CET).