Bull Run [Did you ever play this one, Harry?]. I still remember the box cover (at right), with Jackson standing there with a bandaged hand and some idiot at his side firing a pistol at an unreasonable range. It wasn't even that great of a wargame/conflict simulation/historical strategy game, and I soon switched to computer offerings (Apple IIe, no less) from companies like SSI, but it played a large role in steering me toward the Civil War and away from the Napoleonic Wars and WW2.
Board wargaming is still alive and well, though even more of a niche relegated largely to the Internet, conventions, small clubs, and few and far between tiny corners in general hobby shops. Young boardgamers today would be very surprised to know that during the 70s and 80s, department stores and drug stores all over the country stocked serious wargames on their shelves, with games like Empires in Arms selling 200,000 copies. Those days are long, long gone.
The point of all this is my long held belief that wargames in general are a vastly underappreciated (by book publishers*) gateway drug to serious subject reading. The best designed strategic-level games inspire players to actively seek out more information about military, political, diplomatic, social, and economic history. Recently, I purchased a WW1 game and playing it led me to pick up copies of at least 50 books that I would not otherwise have bothered to read. Yet, as far as I can tell from hobby magazines and websites (I've never been to a gaming conference or convention, so I could be wrong about those venues), book publishers have made little or no effort to market their products to the hobby, both the PC and boardgame varieties. To the lament of their suffering spouses, wargamers spend money, lots of it, to further their interest and knowledge, and I can't help but think neglected opportunity exists for book publishers to exploit.
* - reader Chris makes a good point in the comments section about European publishing. Admittedly, my thoughts did not stray outside the U.S. when writing this post.