See study by O. Eisenschiml (1950).
Fitz John Porter (August 31, 1822 – May 21, 1901) (sometimes written FitzJohn Porter) was a career United States Army officer and a Union General during the American Civil War. He is most known for his performance at the Second Battle of Bull Run and his subsequent court martial.
Although Porter served well in the early battles of the Civil War, his military career was ruined by the controversial trial which was called by his political rivals. Afterwards he worked intensely to restore his tarnished reputation for almost 25 years, when he was finally restored to the army's roll.
Porter was promoted to second lieutenant on June 18, 1846 and First Lieutenant on May 29, 1847. He served in the Mexican-American War and was brevetted to captain on September 8, 1847, for bravery at the Battle of Molino del Rey. He was wounded at Chapultepec on September 13, for which he also received a brevet promotion to major.
After the war with Mexico ended, Porter returned to West Point and became a cavalry and artillery instructor from 1849 to 1853, and then became adjutant to the academy's superintendent until 1855. He next served at Fort Leavenworth, Kansas, as assistant adjutant general in the Department of the West in 1856, where he was brevetted to captain that June. Porter then served under future Confederate Albert Sidney Johnston in his expedition against the Mormons in 1857 and 1858. Afterwards Porter inspected and reorganized the defenses of Charleston Harbor, South Carolina until late 1860, when he aided in the evacuation of army personnel from Texas after that state seceded from the Union.
Porter led his division at the beginning of the Peninsula Campaign, seeing action at the Siege of Yorktown. McClellan created two provisional corps and Porter was assigned to command the V Corps. During the Seven Days Battles, and particularly at the Battle of Gaines' Mill, he displayed a talent for defensive fighting. At the Battle of Malvern Hill he also played a leading role. For his successful performance on the Peninsula he was promoted to major general of volunteers on July 4, 1862.
Porter's corps was sent to reinforce Maj. Gen. John Pope in the Northern Virginia Campaign, a reassignment that he openly challenged and complained about, criticizing Pope personally. During the Second Battle of Bull Run, on August 29, 1862, he was ordered to attack the flank and rear of Maj. Gen. Thomas J. "Stonewall" Jackson's wing of the Army of Northern Virginia. Porter had stopped at Dawkin's Branch where he had encountered Maj. Gen. J.E.B. Stuart's cavalry screen. On August 29 he received a message from Pope directing him to attack the Confederate right (which Pope assumed to be Jackson on Stony Ridge), but at the same time to maintain contact with the neighboring division under Maj. Gen. John F. Reynolds, a conflict in orders that could not be resolved. Pope was apparently unaware that Confederate Maj. Gen. James Longstreet's wing of the army had arrived on the battlefield and the proposed envelopment of Jackson's position would have collided suicidally with Longstreet's large force. Porter chose not to make the attack because of the intelligence he had received that Longstreet was to his immediate front.
On August 30 Pope again ordered the flank attack, and Porter reluctantly complied. As the V Corps turned to head towards Jackson's right and attacked, it presented its own (and consequently the entire army's) flank to Longstreet's waiting men. About 30,000 Confederates now assailed Porter's 5,000 or so men and drove through them and into the rest of Pope's forces, doing exactly what Porter most feared would come of these orders. Pope was infuriated by the defeat, accused Porter of insubordination, and relieved him of his command on September 5.
Porter was soon restored to command of the corps by McClellan and led it through the Maryland Campaign, where the corps served in a reserve position during the Battle of Antietam. He is famously said to have told McClellan, "Remember, General, I command the last reserve of the last Army of the Republic. McClellan took his implied advice and failed to commit his reserves into a battle that might have been won if he had used his forces aggressively.
Porter was then involved in mining, construction, and commerce. He served as the New York City Commissioner of Public Works, the New York City Police Commissioner, and the New York City Fire Commissioner. He died in Morristown, New Jersey, and is buried in Green-Wood Cemetery, Brooklyn, New York.