He distinguished himself at the siege of Vera Cruz, in several bold reconnoissances before the battle of Cerro Gordo, for gallant action at Contreras and Churubusco received the brevet of captain, and at Chapultepec won the brevet of major. His plan for the reduction of the City of Mexico was adopted successfully, and he received two honorable wounds in the course of the assault. Subsequently he superintended the construction and repair of fortresses for the defense of New Orleans and Mobile, and other important engineering duties, with promotion to captain in 1853, until on January 23, 1861, he was appointed superintendent of the United States military academy. This position and his rank in the army he resigned February 20, 1861, and on March 1st he entered the Confederate service with the rank of brigadier-general. Placed in command at Charleston, where he received the surrender of Fort Sumter, he was immediately the center of world-wide attention. Then called to command the army of the Potomac, he won still greater fame by the disastrous rout of the Federal army of invasion at Manassas: and was immediately promoted to the rank of general, Samuel Cooper and Albert Sidney Johnston being his only seniors in that grade. In the spring of 1862 he was ordered to Tennessee as second in command to General Johnston, and on the death of that officer took command at Shiloh. On the second day of that eventful struggle it is remembered that a Confederate officer of high rank, flag in hand, led the charge of a Louisiana regiment in one of their desperate charges, and that when remonstrated with for the dangerous exposure he replied with flashing eyes, "At a moment like this, the order must not be to go, but follow." This intrepid leader was the cool-couraged Beauregard, the victor of First Manassas. After the Corinth campaign his health failed, and he was on leave of absence until August, when he was placed in command at Charleston. His defense of that city and harbor is memorable in the annals of war. For nearly two years, with scant and inadequate resources, the Confederates inspired by his leadership held over three hundred miles of coast against formidable attacks. The world will not soon forget the defeat in April, 1863, of Dupont's iron-clads and Hunter's army; the prolonged resistance of the works on Morris Island to attacks by land and sea; the masterly evacuation of works no longer tenable; nor the holding of Fort Sumter in August, 1863, under the most terrible bombardment on record, which battered the works into ruins but left an unconquered flag, until in other quarters the war was lost. In April, 1864, he was called to Richmond, where he organized a little army, defeated Butler and held Petersburg. In October he was appointed commander-in-chief of the division of the West, and in December his department was enlarged to include South Carolina and the Georgia coast. Relieved by General J. E. Johnston in February, 1865, he voluntarily assisted that commander during the closing period and surrendered with him in April, 1865. After the war he resided in New Orleans, became president of two important railroad companies and served as adjutant-general of the State, preserving to an advanced age an alert and active manhood. He died February 20, 1893.