SLEIDANUS, JOHANNES (1506-1556), German his torian, the annalist of the Reformation, was born at Schleiden, near Aix-la-Chapelle. He studied ancient languages and literatures at Liege and Cologne, and law and jurisprudence at Paris and Orleans. Whilst among the humanists of Liege, he had adopted Protestant opinions, and entering the service of Cardinal du Bellay, was employed in the futile negotiations of the French court to make an alliance with the German Protestants against the emperor Charles V. In 1542 he settled at Strassburg. Sleidanus had been accustomed to copy all papers bearing upon the Reformation to which he had access, and Martin Bucer pro posed to Philip of Hesse to appoint him historian of the Ref ormation, giving him a salary and access to all necessary docu ments. Sleidanus began his great work, finishing the first volume in 1545. In that year he went to England in a French embassy to Henry VIII. While there he collected materials for his his tory. On his return he represented Strassburg at the diets of Frankfort and Worms, and went on to Marburg to explore the archives of Philip of Hesse. The war of the league of Schmal kalden interfered with this work, and also prevented the pay ment of Sleidanus, who received a yearly pension from Edward VI. In 1551 Sleidanus represented Strassburg at the council of
Trent, being charged to act also for the imperial cities of Ess lingen, Ravensburg, Reutlingen, Biberach and Lindau. He was afterwards appointed professor of law in Strassburg, and finished his great task in 1554, though lack of money and other misfor tunes compelled him to delay printing. Sleidanus died in poverty at Strassburg in October 1556. The book appeared in the pre ceding year—Cornmentariorum de statu religionis et reipublicae, Carob V. Caesare, libri XXVI.; it was translated into English by John Daws in 1560 and by G. Bohum in 1689. It was so impar tial that it pleased no one, not even Melanchthon. It remains the most valuable contemporary history of the times of the Ref orma tion, and contains the largest collection of important documents.
See H. Baumgarten, Ober Sleidanus Leben and Briefwechsel (1878), and Sleidans Briefwechsel (1881) and A. Hasenclever, Sleidan-Studien (Bonn. 1905).