FREDERICK WILLIAM IV

born Oct. 15, 1795, Clln, near Berlin died Jan. 2, 1861, Potsdam, Prussia king of Prussia from 1840 until 1861, whose conservative policies helped spark the Revolution of 1848. In the aftermath of the failed revolution, Frederick William followed a reactionary course. In 1857 he was incapacitated by a stroke, and his brother, the future William I, became regent (185861). Additional reading Although there is no definitive biography, E. Lewalter, Friedrich Wilhelm IV (1938), in German, is still indispensable for the study of Frederick.