Baron Adolph Wilhelm August Friedrich von Steinwehr (September 25, 1822 – February 25, 1877) was a German-Brunswick army officer who emigrated to the United States, became a geographer, cartographer, and author, and served as a Union general in the American Civil War. Early life Steinwehr was born in Blankenburg, in the Duchy of Brunswick, Germany, the son of a military family. (His grandfather Friedrich Wilhelm von Steinwehr (1733-1809) was General in the Prussian Army of Frederick the Great) He attended the Brunswick Military Academy and was commissioned a lieutenant in the Brunswick Army in 1841. In 1847 he resigned his commission and emigrated to the United States, settling in Alabama. He served as an engineer in the United States Coast Survey, surveying the United States–Mexico border and Mobile Bay, Alabama, but his desire to serve in a combat position in the Mexican–American War was denied and he returned to Brunswick in 1849, but not before marrying 19-year-old Florence Mary of Mobile, Alabama. He returned to the United States in 1854 and purchased a farm near Wallingford, Connecticut. He later moved to New York state. Civil War At the start of the Civil War, Steinwehr raised a regiment, consisting primarily of German immigrants, the 29th New York Volunteer Infantry Regiment, which he commanded at the First Battle of Bull Run. The regiment was in reserve during the battle, but served an important screening role during the Union retreat. He was promoted to brigadier general on October 12, 1861, and commanded the 2nd Brigade of Louis Blenker's division of the Army of the Potomac. This brigade was moved into Maj. Gen. John C. Frémont's Mountain Department on April 1, 1862, and it fought in the Valley Campaign against Maj. Gen. Thomas J. "Stonewall" Jackson. Fremont's command was expanded into an army corps, which was soon commanded by Maj. Gen. Franz Sigel, another German immigrant. Steinwehr was given the 2nd Division in that corps. It was assigned to the Army of Virginia, under Maj. Gen. John Pope, and participated in the Northern Virginia Campaign, but had little role in the Second Battle of Bull Run. Although the corps joined the Army of the Potomac, the division did not fight at the Battle of Antietam or the Battle of Fredericksburg. The command of what was now called the XI Corps changed to Maj. Gen. Oliver O. Howard in 1863, and Steinwehr continued to command