The correct answer is: "the French Empire"
The First French Empire was leaded by Napoleon Bonaparte, it was the main superpower, and also the largest in size, in continental Europe at the beginning of the 19th century, some decades after the sucess of the Revolution.
The Congress of Viena was subsequently celebrated, between 1814 and 1815, and it gathered many conservative European leaders who sought to design a long-term peace plan, after the French Revolution and others derived from it, and after the Napoleonic Wars.