Nearly all 19th-century German historians made Frederick into a romantic model of a glorified warrior, praising his leadership, administrative efficiency, devotion to duty and success in building up Prussia to a great power in Europe. Historian Leopold von Ranke was unstinting in his praise of Frederick's life and feats, seeing them as raising Prussia to the status of a major European power. Johann Gustav Droysen was even more extolling. Frederick remained an admired historical figure through Germany's defeat in World War I. The Nazis glorified him as a great German leader pre-figuring Adolf Hitler, who personally idolized him.