The Mask of Command (John Keegan, 1987) examines the command styles of Alexander the Great, Wellington, Grant...and Hitler. That fourth section was a weird read for me, because insofar as I'd compare Hitler to Wellington or Grant at all, the labels I would've chosen are Evil and Not Evil. Keegan doesn't deny Hitler's evil, but that's not his point--the focus of that section of the book is on what made him an ineffective commander compared to the other leaders analyzed. And once I got past my aversion to thinking of Hitler as something other than a demon in human form, I decided that was a useful approach, given that Hitler was actually as much a human being as Wellington, or me, or anyone else, and I think we need to be reminded that as a species we have that capacity for evil just as much as we're capable of greatness or ordinariness.
Anyway...that issue aside, this is an informative look at how the nature of military command has changed over time and what makes an effective commander given the changing constraints of military technology. He confirms my high opinion of Wellington and has made me rethink my low opinion of Grant. His conclusion focuses on how nuclear war changes the nature of command by adding unavoidable layers of secrecy and giving the people with the most protection from danger the power to pull the nuclear trigger that they alone won't suffer from. I'd love to see what he says about the post-Cold War, post-9/11 world, and since Wikipedia assures me he's still alive and writing, I might get some of his recent works to do just that.