Polk when, in 1846, he set the final seal upon the settlement with Great Britain of the Oregon frontier. When he did this Polk had already brought about his own war. The judgment on that war expressed at the time in the first "Biglow Papers" has seldom been questioned since, and there seldom can have been a war so sternly condemned by soldiers--Grant amongst others--who fought in it gallantly. The facts seem to have been just as Lincoln afterwards recited them in Congress. The Rio Grande, which looks a reasonable frontier on a map, was claimed by the United States as the frontier of Texas. The territory occupied by the American settlers of Texas reached admittedly up to and beyond the River Nueces, east of the Rio Grande. But in a sparsely settled country, where water is not abundant, the actual border line, if there be any clear line, between settlement from one side and settlement from the other will not for the convenience of treaty-makers run along a river, but rather for the convenience of the settlers along the water-parting between two rivers. So Mexico claimed both banks of the Rio Grande and Spanish settlers inhabited both sides. Polk ordered General Zachary Taylor, who was allowed no discretion in the matter, to march troops right up to the Rio Grande and occupy a position commanding the encampment of the Mexican soldiers there. The Mexican commander, thus threatened, attacked. The Mexicans had thus begun the war. Polk could thus allege his duty to prosecute it. When the whole transaction was afterwards assailed his critics might be tempted to go, or represented as going, upon the false ground that only Congress can constitutionally declare war--that is, of course, sanction purely offensive operations. Long, however, before the dispute could come to a head, the brilliant successes of General Taylor and still more of General Scott, with a few trained troops against large undisciplined numbers, put all criticism at a disadvantage. The City of Mexico was occupied by Scott in September, 1847, and peace, with the cession of the vast domain that had been coveted, was concluded in May, 1848.