The book begins with Napoleon's retreat from Moscow in 1812, at the point when the rest of Europe realized that Napoleon could be beaten and they began to band together to do so. It ends ten years later with the last of the annual European Conferences and the suicide of Castlereagh. This book is a study of international diplomacy and statesmanship OFF the battlefield, among and between the Allies and France; the eponymous Congress of Vienna does get pride of place, but is not the sole focus by any means.

Mostly a study of personalities: the suave Metternich, Henry Kissinger's hero in modern times; the club-footed Talleyrand, who changed sides within France as easily and as often as Lord Gro in "The Worm Ouroboros"; the mystical and reactionary Tsar Alexander; and mostly Castlereagh, the British Foreign Minister: glacial, inarticulate, overworked and depressed, and (so long as Britain's rule of the seas is not questioned, as indeed it wasn't) totally dedicated to a perfect balance of power. Maybe: Nicolson's sympathies are completely with Castlereagh and Britain (Britain's interests are "our" interests throughout the book), and it's not always clear, reading between the lines, that those interests were as absolutely impartial and altruistic as he makes them sound.