In the winter of 4E 174 and 175, the Emperor regathered his forces for an assault. When he joined the Imperial army in Cyrodiil, he discharged much of his army as "invalids" to detain her. In Hammerfell, Lady Arannelya's attempt to join Naarifin's forces had been foiled by General Decianus, who stopped her advance at Skaven. Naarifin also used the Orb of Vaermina to observe the Imperial army and predict its movements. Naarifin's true aim in the Imperial City was to bring about a prophecy entitled "The Culling" with the support of the Dremora blademaster Reive, a servant of Boethiah, who led a cult in support of Naarifin's plan. The Emperor broke out of the city, retreating to Skyrim. The Dominion, however, crossed the Niben and surrounded the Imperial City on three sides, eventually seizing the city in 4E 174. As the Imperial Navy defended the Niben and Lake Rumare, legions from Skyrim joined the Imperial force in early 4E 173. By the end of the year, Naarifin had reached the Imperial City. Continuing to advance in 4E 172, Naarifin seized Anvil and Bravil. Ĭoncurrently, the Thalmor general and Daedra worshipper Lord Naarifin led a force into Cyrodiil from Elsweyr and seized Leyawiin. At least one battle took place in southern Hammerfell, as the soldier Angarion was named "Hero of the Battle of Roseguard". The Dominion forces occupied the country, and the Empire retreated across the Alik'r Desert in the March of Thirst. One, led by Lady Arannelya, entered western Cyrodiil from Valenwood, bypassed its cities, and crossed to Hammerfell to join with Dominion attackers landing on its southern coast. Within days of the declaration of war, two Thalmor armies attacked simultaneously. The Emperor, despite being advised of the Empire's military weakness, rejected the offer and was met with the heads of every Blades agent in Dominion territory.
In 4E 171, the Thalmor sent an ambassador to the Emperor to demand tributes, land, the disbandment of the Blades and the banning of the Talos cult. The Empire of Cyrodiil, on the other hand, became progressively weaker by the accession of Titus Mede II in 4E 168, the Empire had lost the provinces of Black Marsh, Elsweyr, Valenwood, and Morrowind :109 :16, and found its province of Hammerfell severely weakened.
In 4E 29, the Thalmor took control of Valenwood and Elsweyr in 4E 98. After the Oblivion Crisis destabilized Summerset, the Sapiarchs of the Crystal Tower ceded power to the Thalmor and they subsequently seized total control in 4E 22.