The commissioner of the United States was authorized to agree to the establishment of the Rio Grande as the boundary from its entrance into the Gulf to its intersection with the southern boundary of New Mexico, in north latitude about 32 degree, and to obtain a cession to the United States of the Provinces of New Mexico and the Californias and the privilege of the right of way across the Isthmus of Tehuantepec.  The boundary of the Rio Grande and the cession to the United States of New Mexico and Upper California constituted an ultimatum which our commissioner was under no circumstances to yield.

That it might be manifest, not only to Mexico, but to all other nations, that the United States were not disposed to take advantage of a feeble power by insisting upon wrestling from her all the other Provinces, including many of her principal towns and cities, which we had conquered and held in our military occupation but were willing to conclude a treaty in a spirit of liberality, our commissioner was authorized to stipulate for the restoration to Mexico of all our other conquests.

As the territory to be acquired by the boundary proposed might be estimated to be of greater value than a fair equivalent for our just demands, our commissioner was authorized to stipulate for the payment of such additional pecuniary consideration as was deemed reasonable.

The terms of a treaty proposed by the Mexican commissioners were wholly inadmissible.  They negotiated as if Mexico were the victorious, and not the vanquished, party.  They must have known that their ultimatum could never be accepted.  It required the United States to dismember Texas by surrendering to Mexico that part of the territory of that State lying between the Nueces and the Rio Grande, included within her limits by her laws when she was an independent republic, and when she was annexed to the United States and admitted by Congress as one of the States of our Union.  It contained no provision for the payment by Mexico of the just claims of our citizens.  It required indemnity to Mexican citizens for injuries they may have sustained by our troops in the prosecution of the war.  It demanded the right for Mexico to levy and collect the Mexican tariff of duties on goods imported into her ports while in our military occupation during the war, and the owners of which had paid to officers of the United States the military contributions which had been levied upon them; and it offered to cede to the United States, for a pecuniary consideration, that part of Upper California lying north of latitude 37°.  Such were the unreasonable terms proposed by the Mexican commissioners.

The cession to the United States by Mexico of the Provinces of New Mexico and the Californias, as proposed by the commissioner of the United States, it was believed would be more in accordance with the convenience and interests of both nations than any other cession of territory which it was probable Mexico could be induced to make.