Great PlagueGreat Plague - "The waning of the Northmen of Rhovanion began with the Great Plague, which appeared there in the winter of 1635 and soon spread to Gondor.  In Gondor the mortality was great, especially among those who dwelt in cities.  It was greater in Rhovanion, for though its people lived mostly in the open and had no great cities, the Plague came with a cold winter which horses and men were driven into shelter and their low wooden houses and stables were thronged; moreover they were little skilled in the arts of healing and medicine, of which much was still known to Gondor, preserved from the wisdom of Númenor.  When the Plague passed it is said that more than half of the folk of Rhovanion had perished, and of their horses also." ~Unfinished Tales (Cirion and Eorl)