Rudolf II, Holy Roman Emperor
In 1610, Schönberg was appointed commander of a regiment of Dutch troops. He was also named Governor of Düsseldorf. With the outbreak of hostilities in the War of the Jülich succession, he participated in the siege of Jülich to retake the fort at Jülich from the forces of Rudolf II, Holy Roman Emperor. When the fort finally fell, Schönberg made out well in the plundering that followed.