I think it has to do with Trist’s general sense of the war, which he considered an unjust endeavor on the part of the United States and a detestable affair. For example, as Trist and the Mexican representatives were ready to sign the treaty on February 2, 1848, Bernardo Couto said to Trist “this must be a proud moment for you; no less proud for you than it is humiliating for us." To this Trist replied, "we are making peace, let that be our only thought." Later on Trist wrote to his wife, "Could those Mexicans have seen into my heart at that moment, they would have known that my feeling of shame as an American was far stronger than theirs could be as Mexicans. For though it would not have done for me to say so there, that was a thing for every right minded American to be ashamed of, and I was ashamed of it, most cordially and intensely ashamed of it." This is why he decided to stay in Mexico and negotiate the treaty, because he felt that the war against Mexico was the product of deliberate aggression from the United States and because of this he wanted to sign the least possible oppressive treaty that could still be ratifiable by the US Congress.

• Robert W. Drexter, 1991. Guilty of Making Peace: A Biography of Nicholas P. Trist, University Press of American, Lanham, Maryland