FREDERICK IV. (1574-1610), elector palatine, surnamed the Upright, son of Elector Louis VI. and of Elizabeth of Hesse, was born in 1574, succeeded his father under the guardianship of his uncle John Casimir in 1583, and after the death of the latter in 1592 ruled as independent governor. His reign is chiefly of importance for the steadfast and firm support he rendered to the Protestant cause. Under his auspices the Protestant union of Germany was formed in 1601. Mannheim, which had greatly increased through the influx of Protestant refugees, was raised by him to the rank of a town. He died in 1610.