The Mexican War (1846-48) in the Global Context of 19th Century Imperialism

Great Britain was the major imperialist power of the mid-19th century, and its holdings included huge swaths or North America and Canada as well as large investments in Latin America, including Mexico. Given its interests in the Western Hemisphere on the one hand, and its military prowess on the other, why did Great Britain go along with the United States' expansionist moves toward Mexico? In an era when the U.S. was still a wannabe "Great Power," how did the upstart nation double its size at the expense of Mexico with the apparent assent of the dominant powers of that time? Alex Saragoza is an associate professor of History in the Department of Ethnic Studies at UC Berkeley.