The Province of New Mexico, according to its ancient boundaries, as claimed by Mexico, lies on both sides of the Rio Grande. That part of it on the east of that river was in dispute when the war between the United States and Mexico commenced. Texas, by a successful revolution in April, 1836, achieved, and subsequently maintained, her independence. By an act of the Congress of Texas passed in December, 1836, her western boundary was declared to be the Rio Grande from its mouth to its source, and thence due north to the forty-second degree of north latitude. Though the Republic of Texas, by many acts of sovereignty which she asserted and exercised, some of which were stated in my annual message of December, 1846, had established her clear title to the country west of the Nueces, and bordering upon that part of the Rio Grande which lies below the Province of New Mexico, she had never conquered or reduced to actual possession and brought under her Government and laws that part of New Mexico lying east of the Rio Grande, which she claimed to be within her limits. On the breaking out of the war we found Mexico in possession of this disputed territory. As our Army approached Sante Fe (the capital of New Mexico) it was found to be held by a governor under Mexican authority, with an armed force collected to resist our advance. The inhabitants were Mexicans, acknowledging allegiance to Mexico. The boundary in dispute was the line between the two countries engaged in actual war, and the settlement of it of necessity depended on a treaty of peace. Finding the Mexican authorities and people in possession, our forces conquered them, and extended military rule over them and the territory which they actually occupied, in lieu of the sovereignty which was displaced. It was not possible to disturb or change the practical boundary line in the midst of the war, when no negotiation for its adjustment could be opened, and when Texas was not present, by her constituted authorities, to establish and maintain government over a hostile Mexican population who acknowledged no allegiance to her. There was, therefore, no alternative left but to establish and maintain military rule during the war over the conquered people in the disputed territory who had submitted to our arms, or to forbear the exercise of our belligerent rights and leave them in a state of anarchy and without control. Whether the country in dispute rightfully belonged to Mexico or to Texas, it was our right in the first case, and our duty as well as our right in the latter, to conquer and hold it. Whilst this territory was in our possession as conquerors, with a population hostile to the United States, which more than once broke out in open insurrection, it was our unquestionable duty to continue our military occupation of it until the conclusion of the war, and to establish over it a military government, necessary for our own security as well as for the protection of the conquered people.