The Argonian resistance to the Daedric Invasion of Tamriel occurred at some point in 3E 433, after the Battle of Kvatch and the beginning of the Crisis. Oblivion Gates opened in all provinces of the Empire, including Black Marsh. Despite claims by High Chancellor Ocato that the Imperial Legion was fully committed to fighting the war in the provinces, at least one garrison—Fort Swampmoth—was known to have been recalled. Most settlers and non-Argonians were leaving Black Marsh at this time; the Argonians themselves were mostly left to their own devices when the Daedra attacked.
The exact progression of events is unknown; however, an Argonian political faction known as the An-Xileel managed to rally the natives and push back at Mehrunes Dagon's forces with a native might unmatched in any other province save Cyrodiil itself, where Martin Septim likewise pulled the Counties together at a battle at Bruma. The Argonian forces apparently managed to flood into Oblivion itself, fighting and winning against the Daedra on their own turf. The Dremora lieutenants were forced to close their own Gates to prevent being overrun, something unheard of anywhere else. The An-Xileel and their resistance managed to hold Black Marsh until Martin defeated Dagon in the Imperial City and closed all the Gates forever.
Following the Crisis, the An-Xileel emerged as the dominant political force in Argonia, and managed to restore the province's independence in the following years due to the Thalmor inciting an uprising. The Argonians remained a force to be reckoned with, nearly destroying the Dunmer of Morrowind, as well as suppressing any remnants of the Empire in the region. This event was known as the Accession War. By 4E 40, Black Marsh was still independent of the new empire under Titus Mede.
- An Elder Scrolls Novel: The Infernal City (mentioned only)