Warning: responding to posts from August, rambling a bit. Trying very hard to avoid real politics here, please stop me if I go too far.
The US Civil War is not that well known outside North America, you know.
Indeed. From a non-American perspective myself, the only American Civil War battle anyone outside the US is likely to have heard of is Gettysburg, and even then it's just a vague sense of a bloody battle, Confederates charging at prepared lines and getting slaughtered, and so on.
As far as I know, the American Civil War - from my perspective in Australia, at least - is not seen as being massively interesting, especially on the tactical or strategic level. There's a nod to the idea that it's an example of proto-industrialised-war. It's a transitional war: halfway between two very distinct and famous styles of war. Napoleonic-style column warfare was ceasing to work, but it hadn't quite gotten to the point of, say, Omdurman, or even the Russo-Japanese War. Most of what we know about the American Civil War is slaves, Lincoln, Ford's Theatre, and so on. It seems more interesting as a cultural event than as a military one.
In terms of historical prominence and strategic... interestingness, so to speak, I'd compare it unfavourably to the Napoleonic Wars. We know about Napoleon: Austerlitz, Jena, the march into Russia, Trafalgar, Waterloo, and so on. Yet I don't think I've read many BattleTech characters referring to early modern European wars.
I follow. Plus the history the characters in the 31st century know is written primarily by the Star League and its successors, which in turn are successors of Space America.. and Space America can reasonably be expected to have biases that are relatable to most BT fandom.
That argument always seemed odd, to me, because I would have said that American culture is conspicuously under-represented in BattleTech. British of all sorts (that is, English, Scottish, Irish; alas, I have not managed to find the Space Welsh yet) are very over-represented, as are German/Scandinavian influences (with the Lyrans, Rasalhague, and the Ghost Bears, we have three distinct vaguely Nordic factions). Japanese are a little overrepresented as well: not only do we have the Draconis Combine, the Lyrans, FedSuns, and FWL all have token Space Japan planets.
But I can't really find much in BattleTech that is noticeably Space America. I guess I've heard of the Taurians as Space Texas? But for the most part American influences are limited to Terra, and a few worlds near it. New Dallas is the only one to immediately spring to mind.
My usual assumption was that there is no visible 'American' culture in space because, as a rule, people brought ethnicities, or deep-rooted, millennia-old cultures with them to the stars. To put it another way, the United Kingdom never went to the stars: English or Scottish culture or the like did. Nations didn't go. Cultures did. That might put the younger American culture at a disadvantage? The visibly 'American' worlds, then, are mostly around Terra (since the US was one of the first off the mark into space and settled the best, closest worlds), and were thus devastated in war and didn't end up setting the cultures of the great houses. Then American culture in general didn't have the sheer penetration of Japanese or German or Chinese or Hindu (a religious identity as well, even stronger).
Finally, a lot of it might just be the luck of the draw. Local planetary cultures vary widely, but most large states in BattleTech have made some effort to establish an interplanetary supraculture, so to speak, that is overlaid on local cultures and becomes normative for nobles and interplanetary elites. So that's Japan for the Combine, German for the Commonwealth, Han Chinese for the Capellans, a sort of Arthurian mash-up for the Suns, and, well, the League doesn't really have one, but then, maybe that's one of the reasons they're constantly fighting each other. So maybe there are lots of American-ish local cultures; it's just that none of them ever became a great house superculture.
Given that most of the viewpoint characters in the novels I've read are military officers or personnel, it makes sense they would reference historic battles. There are good reasons why the battles of Hannibal, Caesar, Wellington and so on are studied, and it's unlikely the lessons will have been completely replaced 1000 years in the future. More diversity in references would be good - the Alamo wasn't the only doomed heroic stand for example, Thermopyle would make a perfectly acceptable alternative ;)
Or he could choose the Taurian 400 at the Corigan Hills. ;)
A good reference to BattleTech's own history not only helps make the universe seem larger and makes the characters seem less anachronistic, it also helps cross-sell other BattleTech products! :D