This is largely drawn from a "Lessons Learned" report that the US government did in 2020, and the Washington Post first FOIAed, then sued the feds to get, with the addition of a couple oral history projects, and a bunch of found documents. I gather the originals are all online, and would fill an encyclopedia, so this is the more digestible version. (If you find literally anything about this war at all digestible.) Due to the nature of the sources, the focus is extremely U.S.ian, though there are mentions of NATO members, and even the occasional Afghan (usually ones working for NATO). It's not meant to be a comprehensive overview of the war, and spends very little time on individual battles, as the story it's telling is mostly policy in praxis, or I guess the praxis of not having a policy.

I remember spending most of this war being somewhat confused as to what was going on, which might have been a combination of a) no one else knowing what was going on either, b) everyone lying about what they did know. I thought this book did a fairly good job of explaining both those points, and I now have a lot more (depressing) clarity on how things went: i.e. poorly. The general conclusion is that you should have war aims, some kind of theoretical background/science on what you're trying to do, and some familiarity with the culture in question. Also, only invade one country at a time (or don't invade anyone at all).

I'd like to read something with more Afghan perspectives, but I thought this was a good summary otherwise.