And what a disastrous Second War for Independence the War of 1812 tended to be for the infant US with the major exception of the Battle of New Orleans fought after the treaty of peace was signed. Theodore Roosevelt in his magisterial The Naval War of 1812, written when he was all of 23, understood this:
In spite of the last trifling success, the campaign had been to the British both bloody and disastrous. It did not affect the results of the war; and the decisive battle itself was a perfectly useless shedding of blood, for peace had been declared before it was fought. Nevertheless, it was not only glorious but profitable to the United States. Louisiana was saved from being severely ravaged, and New Orleans from possible destruction; and after our humiliating defeats in trying to repel the invasions of Virginia and Maryland, the signal victory of New Orleans was really almost a necessity for the preservation of the national honor. This campaign was the great event of the war, and in it was fought the most important battle as regards numbers that took place during the entire struggle; and the fact that we were victorious, not only saved our self-respect at home, but also gave us prestige abroad which we should otherwise have totally lacked. It could not be said to entirely balance the numerous defeats that we had elsewhere suffered on land—defeats which had so far only been offset by Harrison’s victory in 1813 and the campaign in Lower Canada in 1814—but it at any rate went a long way toward making the score even.
Jackson is certainly by all odds the most prominent figure that appeared during this war, and stands head and shoulders above any other commander, American or British, that it produced. It will be difficult, in all history, to show a parallel to the feat that he performed. In three weeks’ fighting, with a force largely composed of militia, he utterly defeated and drove away an army twice the size of his own, composed of veteran troops, and led by one of the ablest of European generals. During the whole campaign he only erred once, and that was in putting General Morgan, a very incompetent officer, in command of the forces on the west bank. He suited his movements admirably to the various exigencies that arose. The promptness and skill with which he attacked, as soon as he knew of the near approach of the British, undoubtedly saved the city; for their vanguard was so roughly handled that, instead of being able to advance at once, they were forced to delay three days, during which time Jackson entrenched himself in a position from which he was never driven. But after this attack the offensive would have been not only hazardous, but useless, and accordingly Jackson, adopting the mode of warfare which best suited the ground he was on and the troops he had under him, forced the enemy always to fight him where he was strongest, and confined himself strictly to the pure defensive—a system condemned by most European authorities, [Footnote: Thus Napier says (vol. v, p. 25): “Soult fared as most generals will who seek by extensive lines to supply the want of numbers or of hardiness in the troops. Against rude commanders and undisciplined soldiers, lines may avail; seldom against accomplished commanders, never when the assailants are the better soldiers.” And again (p. 150), “Offensive operations must be the basis of a good defensive system.”] but which has at times succeeded to admiration in America, as witness Fredericksburg, Gettysburg, Kenesaw Mountain, and Franklin.