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.

By the joint resolution of Congress of March 1, 1845, “for annexing Texas to the United States,” the “adjustment of all questions of boundary which may arise with other governments” was reserved to this Government.  When the conquest of New Mexico was consummated by our arms, the question of boundary remained still unadjusted.  Until the exchange of the ratifications of the late treaty, New Mexico never became an undisputed portion of the United States, and it would therefore have been premature to deliver over to Texas that portion of it on the east side of the Rio Grande, to which she asserted a claim.  However just the right of Texas may have been to it, that right had never been reduced into her possession, and it was contested by Mexico.

By the cession of the whole of New Mexico, on both sides of the Rio Grande, to the United States, the question of disputed boundary, so far as Mexico is concerned, has been settled, leaving the question as to the true limits of Texas in New Mexico to be adjusted between that State and the United States.

Under the circumstances existing during the pendency of the war, and while the whole of New Mexico, as claimed by our enemy, was in our military occupation, I was not unmindful of the rights of Texas to that portion of it which she claimed to be within her limits.  In answer to a letter from the governor of Texas dated on the 4th of January, 1847, the Secretary of State, by my direction, informed him in a letter of the 12th of February, 1847, that in the President’s annual message of December, 1846—­

You have already perceived that New Mexico is at present in the temporary occupation of the troops of the United States, and the government over it is military in its character.  It is merely such a government as must exist under the laws of nations and of war to preserve order and protect the rights of the inhabitants, and will cease on the conclusion of a treaty of peace with Mexico.  Nothing, therefore, can be more certain than that this temporary government, resulting from necessity, can never injuriously affect the right which the President believes to be justly asserted by Texas to the whole territory on this side of the Rio Grande whenever the Mexican claim to it shall have been extinguished by treaty.  But this is a subject which more properly belongs to the legislative than the executive branch