Other than the man for whom the first Sacher torte was made you mean? He was the most powerful statesman of his time, the so-called “arbiter of Europe” who oversaw the joint effort to redraw the map after the 25 years of turmoil that began with the French Revolution in 1789 and finished with the defeat of Napoleon in 1814. That joint effort was known as the Congress of Vienna (held in you-know-where) and it brought together the four main powers that were allied against Napoleon: Austria, Russia, Prussia and Great Britain.
Contrary to what you might think, the Congress wasn’t really about punishing the French, even though Napoleon had pretty much managed to obliterate Europe trying to put all his crazy utopian ideas into practice. Rather the idea was to punish France just enough (and by extension reward the allies just enough) to balance the big five powers so they couldn’t make war on each other. By that yardstick the Congress of Vienna was a smashing success, since nobody fought anyone else with any great intensity for 40 years.
From the point of view of social reformers, however, it was something of a setback, since from then on the governments of Europe were in no mood for anybody’s big revolutionary ideas. Having harnessed the power of national conscription and industrial weapons production, Napoleon had managed to marshal armies of a size the world had never seen before. The destruction and upheaval were unprecedented. And then there were the revolutionaries, who’d tried to re-name the days of the week and the months of the year, for goodness sakes! No more. The message from on high was: enough monkey business, the grownups are back in charge. Old aristocratic families were returned to power. Social order, religion and adherence to tradition were the new ethos. It was called the Conservative Order and it prevailed in Europe until the masses rose again in 1848, but that’s another story.
Metternich was the prime mover behind all of this, which meant he was no small-potatoes Austrian prince. He was the post-Napoleonic era’s most powerful man. So if you’re wondering how a simple chocolate sponge cake with apricot filling ever got such incredible name recognition, you might start there.