The first efforts to agree upon a treaty of peace failed.  Active operations were resumed, and so weakened Mexico that she was left no alternative but to make “peace such as her powerful and successful enemy might dictate.”  By the Constitution of Mexico the office of President in case of a vacancy devolved upon the president of the Supreme Court provisionally; but there was no president of the Supreme Court in September, 1847, the last incumbent having died, and no successor having been elected when Santa Anna resigned.  Congress, whose duty it was to elect this officer, could only be convened by proclamation of the President, but, as is seen, there was no President.  In this unfortunate state of affairs, the most influential of the Moderado party, with the hope of preventing anarchy, then greatly threatened, if it had not already raised its head, and conclude terms of peace, prevailed upon Pena y Pena, an able and enlightened jurist, statesman, and patriot, and senior judge of the Supreme Court, to assume the provisional presidency.  He was recognized by the State authorities, and pledges were given that they would uphold and defend it against all intriguers opposed to peace, through the non-existence of a government competent to make it.  It was known that Pena was not averse to peace.

Mr. Nicholas P. Trist, the commissioner on the part of the United States, upon the formation of the new Government, made propositions for a conference of representatives.  Owing to the fact that the Mexican Congress had to be called together to elect a President ad interim to serve until January 8, 1848, the overtures of Mr. Trist could not be entertained.  By a combination between the Puro party and the adherents of Santa Anna and other factions, the Moderado party came very near being defeated, but the latter were successful and elected General Don Pedro Maria Anaya ad interim President; and Pena y Pena and General Mora y Villamil, both in favor of peace, were made respectively Minister of Foreign Relations and Minister of War.

Negotiations were now again formally undertaken.  The Mexican Government was represented by Senores Conto, Atristain, and Cuevas.  The commissioners of the respective countries met at Guadalupe Hidalgo, three miles from the City of Mexico.  After many meetings, long conferences, and discussions, a treaty of peace, friendships, and limits between Mexico and the United States was concluded and signed February 2, 1848.

A synopsis of the treaty is given.  Some of the articles are given in full, as the fifth, which secured to the United States the great State of California with its incalculable wealth in mineral and agriculture resources, and the territory of New Mexico, also rich in all that Nature can yield.

  Treaty of Guadalupe Hidalgo, concluded February 2, 1848. 
  Ratifications exchanged at Queretaro, May 30, 1848.  Proclaimed July
  4, 1848.