In 1814 Napoleon was overthrown and exiled to Elba, the Pope returned to Rome, Catholic kings returned to Paris and Madrid and Naples and Turin, exiled bishops or priests poured back into their homelands. For a hundred days of 1815 Napoleon returned to France and the French king fled again from Paris and the Pope fled again, this time to Genoa.
In the air was the feeling of Restoration, of a return to a due order and right which existed before the Revolution. But the Catholic Church of 1815 could not resemble the Catholic Church of twenty years before.
Napoleon was overthrown by the armies of Prussia, Russia, Austria, and Britain. Of these victor powers only one was Catholic.
The first change in the place of the Catholic Church was the failure to make good the political losses of the revolutionary years. The balance of power shifted.
Before the Revolution the great powers of Europe were Britain, France, Austria, and Spain with its vast overseas empire in the Americas: three Catholic powers and one Protestant. In addition Poland was a Catholic country, the southern Netherlands (Belgium) was ruled by Catholic Austria, much of the Rhineland was ruled by Catholic archbishops, and Portugal had another vast overseas empire.
Now the great powers were Britain, Austria, Prussia, and Russia; one Catholic power to three non-Catholic. France lay defeated and weak; Spain lost its empire and was a power no longer; Prussia, already formidable in the eighteenth century, gained vastly by its new lands in west Germany; Russia, already formidable in the eighteenth century, entered Europe; Britain won a new empire. Poland ceased to exist, and a majority of Poles lived under non-Catholic rulers; the southern Netherlands (Belgium) was placed under the Protestant king of Holland; the Rhineland archbishops lost their secular princedoms and were nothing but archbishops. And across the ocean a new power, the United States, Protestant in feeling and in its leaders, ceased to be negligible.