Born Apr. 10, 1829, in Xanten; died Dec. 24, 1891, in Frankfurt am Main. German Catholic historian.
Janssen became a priest in 1860. His political views were close to those of the Catholic Center Party. His principal work, The History of the German People Since the End of the Middle Ages (vols. 1–8, 1876–94), covers the period from the mid-15th century to the beginning of the Thirty Years’ War of 1618–48. Janssen denied the existence in pre-Reformation Germany of any grounds for social and political discontent; he distorted the history of the Reformation and the Peasant War of 1524–26. He characterized Lutheranism as the sole source of all of the radical and revolutionary movements of the 16th century. Janssen’s biases were evident in his efforts to emphasize the importance of the concept of a “Greater German” empire and the traditions of Hapsburg politics and in his attempts to stress the role of the papacy in the struggle with the revolutionary movement in Germany.