Frederick William was the king of united Prussia from 1640 to 1688. Frederick inherited the duchies of Brandenburg and Prussia and united them into an empire.
Frederick was concerned with the growing powers of Sweden and Saxony, so he decided to establish a huge standing army. By the time it was created, it amounted to three percent of the population.
As a result, there were relatively heavy taxes on the people. The diets (local councils that announced laws for the towns, and helped the king make important decisions), gave Frederick the power to create and de-create taxes without them. He never summoned them again.
Frederick was tolerant religiously. He issued the Edict of Potsdam at the same time as the Edict of Nantes was revoked in France, extending religious toleration. Frederick invited Protestants and fleeing non-Catholics into his empire. He had a mixed empire religiously. He himself was a Calvinist.
Frederick William was a relatively good king. Even though he taxed excessively, the people were relatively peaceful and not unhappy under his rule. He left a much improved empire to his son, Frederick I.