William, Count of Nassau-Siegen

William, Count of Nassau-Siegen, German: Wilhelm Graf von Nassau-Siegen, official titles: Graf zu Nassau, Katzenelnbogen, Vianden und Diez, Herr zu Beilstein, was Count of Nassau-Siegen, a part of the County of Nassau from 1624 to 1642. A member of the House of Nassau-Siegen, a cadet branch of the Ottonian Line of the House of Nassau, he was a professional soldier who served in the armies of the Hanseatic League and the Republic of Venice, then with the Dutch States Army during the Eighty Years War. Promoted field marshal in 1633, he was successively governor of Emmerich, Heusden and Sluis.