The Knahaten Flu (also known as the Knahaten Plague), along with the Thrassian Plague, was one of the deadliest diseases to infect the populace of Tamriel, lasting for 43 years, from the year 2E 560 to 2E 603.
There are two theories of who or what caused the Knahaten Flu. One account speaks of an Argonian shaman who, in retaliation to the awful treatment of his people by the other races, created the disease "through a manipulation of their cherished spore-trees" – the Hist. Another account attributes the disease to natural causes. Being that the Argonians were immune to the Flu, and that the previous plague of such mass proportions was artificial, the former story was popularly accepted.
The Knahaten Flu began in the city of Stormhold in 2E 560, and quickly spread to every corner of Black Marsh and beyond, killing all non-Argonians. It continued to plague Tamriel unabated, until finally, four decades later, in the year 2E 603, the last cases of the Flu were being documented.
No symptoms or death toll of the disease are known. However, the Flu almost completely destroyed the non-Argonian population of Black Marsh, instilling fear of the province for centuries to come. Even long after the threat has passed, no human had dared to enter it. Only Dunmer slavers of House Dres, with their entire economy dependent on the slave workforce, remained there. It was said that even Tiber Septim himself thought twice before invading Black Marsh. The scare of the disease lasted late into the Third Era, when a mass panic was created with an alleged relapse of the Flu.
Regardless of source of the disease, the situation in Black Marsh before and after the Flu was quite favorable to the Argonians. After the dissolution of the Second Empire, following the assassination of Potentate Savirien-Chorak, Cyrodiil lost most of its grip on the control of Black Marsh. After the Flu had stricken the province, that grip completely faded away.
The Knahaten Flu also made the Summerset Navy rethink their regulations concerning food.
The Knahaten Flu was quite widespread, having engulfed most of Tamriel, from Black Marsh where it started, to southern Morrowind and across the Topal Bay to Elsweyr, and from there to Valenwood, Cyrodiil, Hammerfell and even High Rock.
The Flu managed to destroy cities, religions and even entire cultures. The most notable people to fall victim to it were the royal family of Wayrest, except for the future king Emeric and the hero Oreyn Bearclaw, who performed many good deeds in Valenwood before succumbing to the disease. Also in Valenwood, the Flu was the cause for the abandonment of worship of Z'en.
Entirety of Elsweyr suffered greatly from the Flu. It was alleviated only with the help of the Altmer who saved many lives, indebting the Khajiiti to them. The city of Senchal suffered the most. A strain of the disease flew across the channel and infected most of the populace. There was damage to the city itself, as paranoia raged rampant and entire sections of the city were burned, to try to slow down the Flu, never to be rebuilt again. An account from three hundred years later said that visitors to Senchal could still see the "charred skylines on the periphery, as black and jagged as the teeth of the nearest sugar junkie, begging for cake."
 Kothringi and the Crimson Ship
However, those most affected by the Knahaten Flu were the human population of Black Marsh. Most notable among them were the native silver-skinned Kothringi, who were completely exterminated by it. One of the most famous episodes of those troubled times was that of the Crimson Ship. Filled with infected Kothringi refugees, it left the shores of Black Marsh on the 9th of First Seed, 2E 563, only to be turned back at every port. After a year on the sea, they reached Hammerfell and with no one to shelter them, they sailed west, never to be seen again. Out of their guilt, the people of Hammerfell honor 20th of Rains Hand as the Day of Shame. Nobody leaves their house, for it is told that the Crimson Ship would return on this day.
- ^ a b c d Pocket Guide to the Empire, 1st Edition: The Wild Regions — Imperial Geographical Society, 2E 864
- ^ a b c d e f g h Pocket Guide to the Empire, 3rd Edition: The War with the Trees: Argonia and the Black Marsh — Imperial Geographical Society, 3E 432
- ^ a b c Pocket Guide to the Empire, 1st Edition: The Elsweyr Confederacy — Imperial Geographical Society, 2E 864
- ^ a b c d Tamriel Timelines, The Daggerfall Chronicles — Ronald Wartow
- ^ Dreekius in Redguard
- ^ a b Pocket Guide to the Empire, 3rd Edition: The Seat of Sundered Kings: Cyrodiil — Imperial Geographical Society, 3E 432
- ^ Pocket Guide to the Empire, 3rd Edition: All the Eras of Man, A Comprehensive History of our History — Imperial Geographical Society, 3E 432
- ^ The Epic of the Grey Falcon — Anonymous. Translated by Anido Jhone, Royal Archaeologist
- ^ a b Varieties of Faith in the Empire — Brother Mikhael Karkuxor
- ^ a b Holidays in Daggerfall
- ^ a b Travails and Triumphs of a Monarch — His Majesty King Emeric
- ^ Tamrielic Lore — Yagrum Bagarn
- ^ Introduction to the Lore of The Elder Scrolls Online