Jülich (yü´lĬkh), former duchy, Germany, between Cologne and Aachen. At first a county, Jülich was raised to a duchy in 1356, and in 1423 it was united with the county of Berg. After the extinction of the Jülich line, both Jülich and Berg passed (1521) to Duke John III of Cleves (see Cleves, duchy of). The struggle that broke out in 1609 for the succession to the territories of the dukes of Cleves ended in 1666. Jülich and Berg passed to the Palatinate-Neuburg branch of the Bavarian house of Wittelsbach and the rest to the electors of Brandenburg. Occupied by the French from 1794 to 1814, the territory was assigned (1815) to Prussia at the Congress of Vienna.

Jülich, town (1994 pop. 31,780), North Rhine–Westphalia, W Germany. It has some light industry and is the seat of a nuclear research center. Originally a Roman settlement known as Juliacum, Jülich was chartered in the mid-13th cent. and served as the capital of the former duchy of Jülich. The town was almost totally destroyed in World War II.