The Lord of the Rings: Shadow of the East
The dreadful plague that swept across Middle-earth in the middle years of the Third Age. It came out of the lands east of Rhovanion in late III 1635, and first affected the Northmen who lived there. It was said that half of that people perished.
The plague soon found its way to Gondor, and in T.A. 1636 many of its people died. Worst affected was the city of Osgiliath on the Great River, and King Telemnar was lost with all of his children (at the same time the White Tree of Minas Anor also died). With such loss of life in Gondor, its guard on Mordor was abandoned. Some said that the Dark Plague was the creation of Sauron, who had intended for Gondor to cease its watch on the borders of his Dark Land.
From Gondor the plague spread northwards. It was at this time that Calenardhon became largely deserted, and Minhiriath was ravaged, remaining almost uninhabited throughout the rest of the Age. Cardolan suffered greatly, and the sickness took all the remaining Dúnedain of that land. By III 1637 the plague had reached the borders of the Shire, founded just thirty-six years earlier. It finally reached as far as the northern parts of Arthedain, but by this time it had become less virulent, and eventually it came to an end, but not before millions had perished.