The Duchy of Julich-Berg was a historical territory located in present-day western Germany. It emerged in the late Middle Ages and was known for its strategic position along trade routes. The duchy was formed through the union of the Duchy of Jülich and the County of Berg in the 15th century. Throughout its history, the duchy experienced various political changes, including conflicts and territorial disputes. It was part of the Holy Roman Empire and later became involved in the Thirty Years' War. The duchy eventually fell under the control of the Electorate of Brandenburg in the 17th century.