John Mansfield (August 1822May 6, 1896) was an American lawyer, Republican politician, and Union Army officer in the American Civil War. He commanded the 2nd Wisconsin Infantry Regiment in the famous Iron Brigade and later served as the 15th lieutenant governor of California. Early life and career Originally from Monroe County, New York, Mansfield emigrated to Wisconsin prior to the Civil War. During the 1850s, Mansfield practiced law in Portage, Wisconsin. Civil War service Following President Lincoln's call for 75,000 state militia troops in April 1861, at the onset of the Civil War, Mansfield was commissioned as captain of Company G, 2nd Wisconsin Infantry Regiment, known as the "Portage Guards." Mustered at Camp Randall in Madison on June 11, 1861, Mansfield's regiment entered as a three-year regiment and departed Wisconsin for Washington, D.C. on June 20 to join the Army of the Potomac. At Washington, Mansfield's regiment was initially brigaded under William T. Sherman along with the 13th New York Volunteer Infantry, the 69th New York Volunteer Infantry and the 79th New York Volunteer Infantry. Mansfield's regiment first saw action at the First Battle of Bull Run in July 1861. Mansfield and the 2nd Wisconsin went on to take part in many key battles of the war as part of the famed Iron Brigade, including South Mountain, Antietam, and Gettysburg. Battle of Gettysburg At Gettysburg, Mansfield had become major of the 2nd Wisconsin and was the 2nd highest ranking officer left in the regiment. The 2nd Wisconsin and the Iron Brigade were part of the 1st Division of I Corps, under Brig. General James S. Wadsworth, and were at the vanguard on the march to Gettysburg. On the first day of fighting, July 1, 1863, the 2nd Wisconsin engaged a Confederate brigade under Brig. General James J. Archer at McPherson Woods. Early in the fighting, 2nd Wisconsin soldier Private Patrick Maloney captured Archer himself, who surrendered his sword to Mansfield. Archer's surrender to Mansfield marked the first capture of a Confederate general officer since Robert E. Lee had assumed command of the Army of Northern Virginia. Later in the first day of fighting, Major Mansfield assumed command of the 2nd Wisconsin after the senior officer, future Wisconsin governor Lucius Fairchild, was shot. Mansfield himself would be wounded later that same day and be forced to relinquish command of the regiment. Following the battle, Mansfield was appointed lieutenant colonel on July