 He was frustrated in building up naval power, lacking ports and sailors.A learned man, he founded a university and established the Berlin library.On 7 December 1646 in The Hague, Frederick William entered into a marriage, proposed by Blumenthal as a partial solution to the Jülich-Berg question, with Luise Henriette of Nassau (1627–1667), daughter of Frederick Henry of Orange-Nassau and Amalia of Solms-Braunfels and his 1st cousin once removed through William the Silent.