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 in his visit to Charles III of Naples 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 Prince-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 and to his successor, Antipope Pope 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 22 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 limself, and the like. The De schismate libri III, completed on 25 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.
Works
Other works are:
De bono regimine Rom. pontificis, dedicated to the new pope
De modis uniendiae reformandi ecclesiam and De difficultate 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 ad privilegia imperil, a glorification of the empire in view of the convocation of the council of Constance
Avisamenta pelcherrima de unions et reformatione membrorum et capitis fienda, a programme of church reform based on his experiences of the evils of the papal system.
Appearances in fiction
A passage from Dietrich of Nieheim's De schismate libri III is used as an epigraph at the beginning of the second chapter of Arthur Koestler's novel, Darkness at Noon: However, this is actually a paraphrase of Dietrich's position in the treatise De modis, as expressed by the German historianLudwig von Pastor, in his book Geschichte der Päpste seit dem Ausgang des Mittelalters, vol. 1, p. 149. De modis is credited in German editions of Darkness at Noon, but von Pastor is not. The paraphrase is about how Dietrich wanted the Holy Roman Emperor to call a General Council, the Pope to bow to the will of Emperor and Council, and for Emperor and Council to do whatever they felt necessary to end the antipope schism. Here is the actual quote from De Modis, from the section 'De modis, loco trium malorum Pontificum, unum bonum eligendi, in Universalis Concilio Constantienst':
