William Makepeace Thackeray's Counterfactual

In my reading about historical counterfactuals I do not recall ever running across the name of William Makepeace Thackeray, but as it happens he indulges in one at paragraph-length in the course of Vanity Fair as the Battle of Waterloo draws near. As he remarks, "[t]hose who like to lay down the History-book, and to speculate upon what MIGHT have happened in the world," may have wondered about Napoleon's timing in returning from exile, and whether his coming just a little later might have made history run another way. While those who study the period are typically taught to the Congress of Vienna as a triumph of statesmanship that helped prevent the outbreak of another general war in Europe for a near century (or from a more critical standpoint, shore up what remained of the waning Old Regime), Thackeray reminds us that it was not all cooperation at the conference. Rather each power, whose "august jobbers [had] assembled at Vienna" was out for what it could get, and arguing over the map of Europe like a band of robbers falling out over the division of the loot, with their mutual enmity the reason why their armies were so prepared to fight at that time--and only Napoleon's return uniting them in "hatred and fear" may have kept them from doing so. Indeed, Thackeray imagines, had Napoleon waited until the robbers actually did fall out before returning, they would not have confronted him with a united front as they did when he actually returned, and perhaps managed to go on reigning in France. However, for my part I wonder less about Napoleon's chances of having been Emperor for a few more years than how the map of Europe, and the attempt to turn back the clock socially and politically across the continent, may have been altered in the course of that timeline's events.