When Prussia absorbed Hanover and then set up the German Empire in 1871, Windthorst dealt with the new state of affairs and became a leader of the all-Catholic Centre Party. It won over 80% of the Catholic vote in a new nation that was one-third Catholic. He opposed Bismarck's harassment of minorities such as Catholics, Hanoverian Guelphs, Poles, Danes, and Alsatians. He argued for natural law as the basis of political rights. He perfected the arts of opposition, forming alliances that could win majorities. The Centre party became what Anderson calls "a liberal party manque." That is, it kept its distance from the anti-Catholic National Liberal Party but championed the rights of minorities, the powers of parliament, and the rule of law against Bismarck's moves.