The war began as a dispute over a declaration by Duke Ferdinand and developed into a full-scale war between the Catholic and Protestant religions, Calvinist and Lutheran. While the war began for religious reasons, it ultimately ended up being a political tool used to limit Habsburg power in Spain. France, a Catholic power, and other anti-Catholic entities gave support to Gustavus Adolphe, who was a deeply religious Protestant fighting largely Catholic Spain. This led to a division of the Holy Roman Empire and divided Germany as Sweden, France and the Catholic Church carved up their territories through political means to increase their own party's popularity.