I am still in the process of reading this but will put in an early recommendation. It is one of the most interesting books I've read in years. There is a reason why The Peloponnesian War is studied at West Point and I now see why historians such as Lord Bullock stressed reading Thucydides in order to understand the modern world. Victor Davis Hanson does an outstanding job of providing a perspective that is often missed.
"No government was as calculating or sober - or blinkered - as Sparta's gerousia, a governing senate of old men who had seen little of civilization abroad and thus were loath to sanction rash action beyond the vale of Laconia. No government was as reckless and dangerous as Athens' assembly, composed of many leaders who had traveled the Aegean. Yet the latter in a minute's fit could call for the execution of a man - or an entire captured city across the seas - on the flimsiest of charges."
"No one foresaw such carnage in 431. Who believed that in just two years, the majestic Pericles would end up covered with pustules, grasping an amulet as he coughed out his life in the fevers of the plague? The millionaire Nicias never imagined that twenty years later he would beg for his life before having his throat slit eight hundred miles away in Sicily. Nor did the handsome Alcibiades, the rage of Athens, envision that he of all people would be murdered by assassins in an obscure hamlet in Asia Minor. Everything considered wisdom at the beginning of the war would be proven folly at its end."