I just read a biography of Andrew Jackson, and I'm nearly finished with John S. D. Eisenhower's history of the 1846-1848 war with Mexico. I generally find post-revolutionary American history depressing, and I expected this to be the most depressing period of all: the time when American racism and imperialism was at its rawest and ugliest. But – maybe because my expectations were so low – I've been somewhat pleasantly surprised. Even Jackson comes off better, at a closer view, than I expected.
What I had not taken into account was that American dealings with the Indians and Mexicans had a good deal more to do with Britain and France than I had imagined. I'm so used to thinking of America as a superpower that I was misinterpreting things. England and France were the superpowers of the day, and any time they came into conflict with the United States they started stirring up Indian revolts and looking for ways to nose into North American territories that were under shaky or dubious authority – which meant, usually, ostensibly Mexican territory. The U.S. was looking for security. It's not a glorious motivation, but it's better than simple self-aggrandizement.
The other thing I'm struck by – coming to this history now, and knowing a lot more about military matters than I did when I first formed my impressions – is that the defeat of Mexico, far from being a foregone conclusion, was one of the most astonishing feats in the history of American arms. Virtually all the advantages – of numbers, terrain, matériel, and motive – were with the Mexicans. American artillery was better – they had done their European shopping more scientifically than the Mexicans – but that was about it. By most ordinary reckonings, the Americans should have lost badly. (The Duke of Wellington, in fact, was sure that the war, and in particular Scott's lunge to Mexico City, would end in an American disaster.) It's hard to avoid the conclusion that the American troops, from generals to privates, were simply, in modern-day parlance, much more empowered and self-reliant than the Mexicans.