NIEM [NYEM, or NIEHEIM], DIETRICH OF (c. 1345-1418), medieval historian, was born at Nieheim, a small town subject to the see of Paderborn. He became a notary of the papal court of the rota at Avignon, and in 1376 went with the Curia to Rome. Urban VI. here took particular notice of him, made him an abbreviator to the papal chancery, and in 1383 took him with him on his visit to King Charles at Naples, an expedition which led to many unpleasant adventures, from which he escaped in 1385 by leaving the Curia. In 1387 he is again found among the abbreviators, and in 1395 Pope Boniface IX. appointed him to the bishopric of Verden. His attempt to take possession of the see, however, met with successful opposition; and he had to resume his work in the chancery, where his name again appears in 1403. In the meantime he had helped to found a German hospice in Rome, which survives as the Institute dell' Anima, and had begun to write a chronicle, of which only fragments are extant. His chief importance, however, lies in the part he took in the controversies arising out of the Great Schism. He accompanied Gregory XII. to Lucca in May 1408, and, having in vain tried to make the pope listen to counsels of moderation, he joined the Roman and Avignonese cardinals at Pisa. He adhered to the pope elected by the council of Pisa (Alexander V.) and to his successor John XXIII., resuming his place at the Curia. In view of the increasing confusion in the Church, however, he became one of the most ardent advocates of the appeal to a general council. He was present at the council of Constance as adviser to the German " nation." He died at Maastricht on the 22nd of March 1418.
Niem wrote about events in which he either had an intimate personal share or of which he was in an excellent position to obtain accurate information. His most important works are the Nemus unionis and the De schismate. Of these the first, compiled at Lucca after the breach with Gregory XII., is a collection of documents which had fallen into his hands during the negotiations for union : papal pronouncements, pamphlets, letters written and received by himself, and the like. The De schismate libri III., completed on the 25th of May 1410, describes the history of events since 1376 as Niem himself had seen them. It was continued in the Historia de vita Johannis XXIII. Other works are De bono regimine Rom. pontificis, dedicated to the new pope (John XXIII.); De modis uniendi ac reformandi ecclesiam and De difficidtaU reformationis in concilia universali, advocating the convocation of a council, to which the pope is to bow; Contra dampnatos Wiclivitas Pragae, against the Hussites; Jura ac privilegia imperil, a glorification of the empire in view of the convocation of the council of Constance; Avisamenta pulcherrima de unione el reformatione membrorum et capitis fienda, a programme of church reform based on his experiences of the evils of the papal system.
For bibliography see Potthast, Bibl. hist, medii aevi (2nd ed., Berlin, 1896), p. 1051, s.v. " Theodoricus de Niem "; and generally see the article on Niem by Theodor Lindner in Allgemeine deutsche Biographie (Leipzig, 1886); and Erler, Dietrich von Nieheim (Leipzig, 1887).
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)