Fitz John Porter, an American soldier, born in Portsmouth, N. H., in 1823. He graduated at West Point in 1845, and served in garrison at Fortress Monroe until the opening of the Mexican war. He was engaged in the siege of Vera Cruz, and in the battles of Cerro Gordo, Contreras, Molino del Rey, Chapultepec, and the assault upon the city of Mexico, in which he was wounded at the Belen gate, and was successively brevetted as captain and major. He was afterward on garrison duty in various places till 1849, when he became instructor of artillery and cavalry at West Point. From 1855 to 1860 he served in various capacities, being from 1857 to 1860 assistant adjutant general of the Utah expedition. At the commencement of the civil war he acted as chief of staff in the department of Pennsylvania and in the valley of the Shenandoah. He was made colonel in the regular army and brigadier general of volunteers in May, 1861, and placed in command of a division in the defences of Washington. At the opening of the peninsular campaign he commanded his division, and was superintendent of the siege of Yorktown. In May, 1862, he was assigned to the command of the 5th corps of the army of the Potomac. He commanded at the battle of Hanover Court House, May 27, and at Cold Harbor, June 27, and was made major general of volunteers.

At the battle of Malvern Hill, July 1, he was in virtual command, posting all the corps as they came upon the field. He commanded his corps during Pope's campaign in northern Virginia. At the second battle of Bull Run his corps, though ordered to advance, failed to appear on the field on Aug. 29, but in the afternoon of the 30th was more actively engaged than any other, nearly a quarter of its members being killed or wounded; to their obstinate resistance it was mainly due that the defeat was not" a total rout. His corps took part in the campaign in Maryland, and was present at the battle of Antietam, Sept. 17; but it was kept in reserve by McClellan, and was only slightly engaged. Pope was greatly displeased with the conduct of Porter at and near Bull Run, Sept. 27-30, and in November preferred charges against him. A court martial was ordered, which began its proceedings on Dec. 1, the charges being now brought, not by Pope, but by Gen. Roberts, who had been Pope's inspector general. The trial continued till Jan. 10, and resulted in a verdict of guilty; and Porter was sentenced, Jan. 21, to be cashiered and "for ever disqualified from holding any office of trust or profit under the government of the United States." The justice of this verdict has been a subject of much controversy.

After leaving the army he engaged in business in New York, was subsequently superintendent of the construction of the New Jersey asylum for the insane, and in February, 1875, was appointed commissioner of public works in the city of New York.