I. biographical name
1620-1688 the Great Elector elector of Brandenburg (1640-88)
II. biographical name
name of 4 kings of Prussia: I 1688-1740 (reigned 1713-40); II 1744-1797 (reigned 1786-97); III 1770-1840 (reigned 1797-1840); IV 1795-1861 (reigned 1840-61)