In 1845 the United States, in a fit of muscular expansionism, annexed the Mexican state of Texas which caused hostilities between the two countries, and a fair amount of confusion among the Texans. Not content with Texas, the US tried violently to expand their territory more with general S. Kearney taking over New Mexico. At the same time captain Frémont annexed Californian territory almost without any bloodshed. With these two moves the US had added fully a quarter more territory to their landspace.
The Mexicans were not in the least amused and when general Zachary Taylor invaded northern Mexico across the Rio Grande he met tough opposition. In a tremendous and bloody battle at Buena Vista Taylor defeated general Antonio López de Santa Ana in a two day conflict in February 1847; but the worst fighting was in central Mexico, where general Winfield Scott’s bombarding of the town of Vera Cruz succeeded in killing hundreds, perhaps thousands of civilians.
Having nearly wiped Vera Cruz off the map, the US moved inland towards Mexico City, with obvious intentions. The Americans fought hotly contested engagements at Molino del Rey and Chapultepec Hill in September, 1847. When Mexico City itself was captured surrender was not long in coming.
The Treaty of Guadalupe Hidalgo in 1848 put an end to hostilities. Dictated by the Americans it confirmed US ownership of Texas and gained control of the huge area which would eventually become New Mexico, Arizona and California (where co-incidentally gold had been discovered in large quantities). The Treaty also made a deadly enemy for the US Army in the hostile form of the Apache tribes. The Indian Wars against this fearless enemy were to last nearly fifty years. The United States agreed to pay Mexico the staggering sum (for then) of fifteen million dollars for this addition to their lands. The question must therefore remain – if the US was prepared to pay this colossal sum in the first place, why bother with the wars in which so many on both sides were killed or maimed? Hand over the cheque and nobody need get even a nosebleed.