Blackwater War The Blackwater War was a twenty - six - year war that occurred in Black Marsh from early 1E 2811 to early 1E 2837 as a result of the Reman Empire ' s advances in the region . The war separated into three distinct Imperial campaigns , the First of which was led by Augurius Bucco , the second by Regulus Sardecus , and the third by Lucinia Falco . Although the general aim of the war was unchanged throughout its nearly three - decade length , each campaign saw radically different strategies and events . First campaign . The first campaign of the Blackwater War began in 1E 2811 . The Fourth Legion , led by young and popular commander Augurius Bucco , saw several massive victories very early on , including a success at the Battle of Argonia . These encouraged the Empire to launch a full - scale invasion of the province later that year , including the more congested , swampy interior . However , as the soldiers of the Fourth Legion progressed farther into Black Marsh ' s inhospitable swamps , they soon encountered numerous problems . Accustomed to fighting in the comparatively tame hills of Cyrodiil , the legionnaires found it difficult to defend themselves against their Argonian foes , who were already aware of how best to conduct military operations in the boggy , wet climate . Disease spread quickly among Imperial forces and was the leading cause of death in the first campaign , killing roughly half of the legionnaires . While the Argonian forces operated with ease , the Legion ' s heavy equipment was of little use in the jungle . Their armor tended to rust as a result of the wetness of the air , and huge amounts of mud slowed soldiers greatly by clinging to their boots and shields . By late 1E 2812 , these hindrances eventually led to much of the Imperial army simply not wearing their heavier cuirasses and greaves , which gave them more leeway in combat but left them with significantly less protection . Additionally , traditional Imperial battle tactics proved futile , as there was no way to effectively keep together organized cohorts of soldiers in the messy geography of central Black Marsh . Groups were frequently split apart and the chain of command lost , which allowed for the better - adjusted Argonian forces to quickly and easily defeat the Imperials . Insubordination and a general lack of morale among legionnaires soon followed . Five years into the war , in 1E 2816 , all but six cohorts of the entire Fourth Legion had perished . General Bucco called in a second legion from Cyrodiil in order to construct a paved road which was called Reman ' s Way , or later Swamp Road , to aid the war effort . The exact purposes of the road were equivocal , although if completed it would most likely have been used to move supplies and soldiers more quickly . However , due to a constant barrage of attacks from the Argonians , few defensive capabilities , and poor working conditions , the project was never more than half - finished . In 1E 2820 , four years after " Bucco ' s Folly , " as the failed road - building attempt was later dubbed , the Fourth Legion had been almost entirely killed off , save an estimated 350 exhausted troops . Bucco himself was almost removed from command via a mutiny , after which he fully realized the futility of his efforts and ordered the Imperial army to retreat from the innermost parts of Black Marsh . A ten - day march led the remnants of the legion to the ancient Argonian pyramid of Xi - tsei , where Bucco intended for his men to rest for a time and then fall back to Cyrodiil . However , the Argonians were able to quickly catch up to them . On the 14th of Last Seed , the Argonian forces completely annihilated the few Legion soldiers left alive . Second campaign . As a result of the catastrophic failure that was Augurius Bucco ' s campaign in Black Marsh , the Imperial Council selected Regulus Sardecus as the new general of the Fourth Legion , which was rebuilt for a second invasion . While the young General Bucco had relatively little experience in combat prior to the war , General Sardecus had been involved in countless battles during his military career so far and was very highly regarded . Sardecus ' war strategy in Black Marsh ' s swamps was infinitely better - suited for the climate and terrain than Bucco ' s . Imperial soldiers were instructed to wear lighter , less constrictive padded leather instead of typical heavy metal Imperial armor to combat the ferocious heat and humidity of the region . Some non - hostile Argonians were consulted for the best methods on how to make use of the jungle ' s resources , and groups of soldiers were taught to operate in relative independence due to the constant fracturing of the army for increased efficiency and soldier morale . However , what most gave Sardecus ' legion an advantage over Bucco ' s was the former ' s use of diplomacy in regards to " disenfranchised " Argonians , who could be bribed or otherwise convinced to fight on the side of the Imperials . By forging alliances with multiple native tribes such as the Archeins and the Shoss - kaleel , Sardecus was able to nearly triple his forces and regain all formerly lost territory by 1E 2823 . Sardecus developed a unique strategy to combat Black Marsh ' s unruly terrain : destroy it . While Bucco and his legions had focused primarily on simply fighting the Argonians , it had not occurred to them that the Argonian ' s greatest advantage over them was their use of the land to their benefit . Sardecus , however , realized that he could cripple Argonian forces by simultaneously launching attacks and also draining swamps , salting rice paddies , and cutting down huge swaths of forest . This strategy worked exceedingly well until the order came down from Elissia Mallicius to set ablaze a peat bog in the vicinity of Stormhold , far to the north . Although there was no reason to believe it would have any undesired effects , the peat bog in question was in fact part of a massive , interconnected network of underground tunnels , which would subsequently be set ablaze because of this . As a result , spontaneous fires were reported all across Black Marsh after several months , even as far away from Stormhold as Gideon and Soulrest , in the southwestern part of the province . Quite some time passed before it was realized that a massive , province - wide fire was occurring . Historian Valenca Arvina described the fires as " an inferno of burning peat and detritus . " Noxious gases and unpredictable eruptions and explosions completely obliterated the marsh ' s environment , and thousands of soldiers on both sides succumbed to the effects of what would be called the " Great Burn " of 1E 2828 , which lasted until at least 1E 2831 . General Sardecus eventually ordered a full retreat from the province to avoid a greater number of casualties . However , before making it back to the Imperial City , he died of an infected wound . The source of this wound is , like many things in this war , contestable . Third campaign . A third and final general , Lucinia Falco , took command of the Fourth Legion in approximately 1E 2833 . Her entire military career had been based in Black Marsh during the Blackwater War , having personally fought in the Battle of Argonia more than twenty years prior . She took Sardecus ' new strategies another step forward and reached out to pirates around Black Marsh , whom she convinced to fight alongside a legion of Diamond Marines from Imperial ranks . Falco also further subdivided her troops into very small yet extremely effective platoons called " redbelts , " each led by officers who had significant experience in the war already . These groups were able to take over most of western Black Marsh with relative ease , but by the time they reached the deeper portions of the province they were slowed tremendously by the terrain once again . Additionally , due to the small size of these platoons , much conquered territory was quickly returned to the hands of the Argonians . The conflict turned into a bloody , terrifying , and very complicated guerrilla war by 1E 2834 . The conflict ended abruptly and without an official declaration of peace in late 1E 2836 largely due to tribal infighting by the Argonians , who simply stopped fighting and returned to their former lives . By 1E 2837 , the Empire had claimed the entire province .