Answer:
First, there is the annexation of Texas which was an initial lost of territory for Mexico in 1845, or at least it became formal. The ensuing Mexican-American War (1846-1848) started as a border conflict, but its outcome accomplished the great goal of westard expansion to the shores of the Pacific Ocean that is part of the Manifest Destiny doctrine. Â Besides, it added millions of square miles to the territory of the US.
Explanation: