Peter Joseph Osterhaus, born January 4, 1823 in modern day Germany, became a popular Union officer during the American Civil War. After a military education in Prussia, Osterhaus became involved in the Revolution of 1848 and was forced to flee to the United States after it failed. After moving several times, Osterhaus finally settled in St. Louis, Missouri. Mid-nineteenth century St. Louis had a large German population, which Osterhaus and other German-Americans used to advance their political and military careers.
Osterhaus entered the Civil War as a major in a Federal Missouri battalion on April 27, 1861. Before fighting at Pea Ridge, Osterhaus participated in the Battle of Wilson’s Creek on August 10th, 1861. In December of that year, Osterhaus was made colonel of the 12th Missouri infantry.
Placed under the command of fellow German Brigadier General Franz Sigel, Osterhaus participated in the march from St. Louis through southwest Missouri that forced Sterling Price and the Missouri State Guard into Arkansas.
On the morning of March 7th, the first day of fighting here at Pea Ridge, Colonel Osterhaus was tasked with meeting the enemy that had skirted the Federal right flank the night of the 6th and threatened the Federals entrenched at Little Sugar Creek. Because the Federals had no idea that the Confederates were moving to attack the rear of the Federal army from the north, Osterhaus was meant to delay the Rebels and scout their movements. With directions to engage the Rebels by moving towards Twelve Corners Church, Osterhaus and his troops discovered that the force moving towards the Federal rear was larger than expected. Osterhaus ordered Colonel Cyrus Bussey to take his six hundred cavalrymen and three artillery pieces to head north on Leetown Road towards Twelve Corners Church. Colonel Nicholas Greusel would follow as fast as possible with the infantry and form up in Oberson’s field, a large field north of Leetown. After a disastrous encounter with Confederate Brigadier General Benjamin McCulloch’s division of the Army of the West, Bussey’s troops fled south through the woods between Foster’s Farm and Oberson’s field and panic stricken, moved past Greusel’s infantry. Despite the cavalry’s panicked retreat, Greusel managed to keep the infantry in line. The Confederates had chased the retreating Federals through the woods to the north of Oberson’s field but stopped just short of the field in order to reconnoiter the Federal position. While attempting to ascertain the Federal position two Confederate generals were killed, Benjamin McCulloch and James McIntosh. Due to the loss of these two leaders, the Confederates in the woods on the west side of Leetown Road remained largely inactive, leaving Confederates in Morgan’s Woods under Colonel Louis Hebert on their own. Osterhaus swung his Federals to the east and surrounded Hebert’s men. This led to the capture of Hebert and the defeat of the Confederates at Leetown. That evening Osterhaus and his troops joined Brig. Gen. Franz Sigel at Ford Farm but ended up near Pratt’s Store where the rested for the next day of battle.
Around dawn, Sigel sent Osterhaus and his troops on a reconnaissance mission towards Ford Farm. When they reached the top of Welfley’s Knoll, Osterhaus recognized the value of that area and informed Sigel. Osterhaus’ troops, along with Sigel, formed around and atop Welfley’s Knoll and placed twenty-one Federal guns facing the Confederates to the west of Telegraph Road. These guns would prove decisive in the Union victory here at Pea Ridge.
After the Battle of Pea Ridge, in June of 1862, Peter Osterhaus was appointed brigadier general of volunteers. He commanded troops during the Vicksburg campaign under Ulysses S. Grant and William T. Sherman, and was wounded at Big Black River. Osterhaus also participated in the events at Chattanooga, Tennessee under Joseph Hooker. During the Atlanta campaign, Osterhaus gained the rank of major general and served under Sherman.
After the Civil War, Osterhaus moved between France, where he was the consul in Lyons, and St. Louis, where he had a hardware business. At the end of his life, he still served the United States as consul in Germany and lived there until he died on January 2, 1917.