SLEIDANUS, JOHANN. — He was the most famous annalist of the German Reformation. Born probably in 1506 at Schleiden in the Eifel from the Philippi family, he received his education at Liège; he seems to have studied at Cologne. The first certain document about him is a letter from the summer of 1530 in which he appears as a humanist of Erasmian leanings, with a warm admiration for Melanchthon, and sees in the German religious revolution a decisive opposition to imperial policy.
From 1533 he spent many years in France: he was in Paris with Johannes Sturm (1534); in November 1538 he enrolled for the licentiate in law at Orléans, and stayed with Cardinal Giovanni du Bellay and his brother François until the death of Francis I. He was at Hagenau on a secret mission with Philipp of Hesse and there met the leaders of the Lutheran movement. In 1544 he was to accompany Cardinal du Bellay to the Diet of Speyer, but they only reached Nancy; Sleidanus remained in Strasbourg and translated into Latin Bucer’s Catechism. This drew the attention of the Landgrave, who saw him as a possible historian, especially since he had gathered material on the Schmalkaldic League. He served as ambassador in England, where he was able to form friendships and collect information. He was at Trent from spring 1551 to April 1552 as an envoy; in 1554 he was with Pier Paolo Vergerio. In 1554–55 his major work, *De statu religionis et reipublicae Carolo V Caesare commentariorum libri XXVI*, was printed in Strasbourg, dedicated to Augustus, Elector of Saxony, and soon banned by the Emperor, criticized by both Protestants and Catholics, because, according to Melanchthon, it told much that would have been better left unsaid forever. Sleidanus died on 31 October 1556; in June of that year he had published *De quattuor summis imperii libri III*. His minor writings were collected in *Opuscula*, Hanover 1608.