The condensation reminds me of a book I mentioned before, Forge of Empires
by Michael Knox Beran. The book traces the 1860s paths of Lincoln, Bismarck and Tsar Alexander II in considerable detail--but then suddenly races through major events like Lincoln's reelection, and virtually jumps over his assassination (discussing it only obliquely after the fact). That's a somewhat unsatisfying literary device, though it remains a very interesting book overall.
