The Oculus (Latin for Eye) was an Imperial organization formed in the aftermath of the Oblivion Crisis to stop insurrections in several provinces, later becoming used as a tool of the Emperor to put down his enemies.
In the aftermath of the Oblivion Crisis, Tamriel was in ruin. With no Septim heir to the throne, the Elder Council was forced to name High Chancillor Ocato potentate until a new emperor could be chosen. Several provinces threatened to break away from the Empire, as well.
Potenate Ocato and the Elder Council formed the Oculus in order to stop rebellious activity in several provinces. The organization consisted of spies and soldiers of the Oblivion Crisis, with members of all races being present. Oculus spies were involved with bringing order to the Summerset Isles, Morrowind, and Argonia.
In Argonia, Oculus agents fought against Black Marsh rebels during the Argonian Uprising, later being pushed out of the province with the rest of the Imperial Legion. In Morrowind, the Oculus was tasked with bringing peace to the Great Houses, as a major civil war took place there during the Oblivion Crisis. The organization improved lines of communication and re-established Imperial order in several towns and cities, while secretly murdering enemies of the Empire.
In the Summerset Isles, Oculus agents assisted the Altmer in rebuilding their province, as it had been utterly destroyed during the Crisis. Arvgus Selenur, the Master of the Oculus, heard rumors of the Thalmor plotting a rebellion, but never acted on these reports, regarding them as hearsay. A spy was, however, implanted into the organzation; she was an Altmer woman named Terya Chamore.
In 4E 10, Potentate Octato was assassinated by unknown forces. The death of Octato began the Stormcrown Interregum, where multiple warlords rose up to try and take the Ruby Throne and declare themselves emperor. The Oculus became a deadly force during this period, evolving a political branch with multiple contacts in the Elder Council and Imperial Watch.
In 4E 16, a Colovian warlord named Titus Mede captured the Imperial City and was declared emperor (with the shadow support of the Oculus).
In 4E 22, Arvgus paid dearly for his ignorance of the Thalmor; several Altmer soldiers stormed his home in Alinor and murdered his entire family as the Alinor Uprising began. The Third Legion was being pushed back en masse all across the Summerset Isles. Oculus agents in the province were being hunted down and butchered, alongside members of the Blades.
Several weeks later, Imperial administration of the province ended when the last Legion cohort fled the Isles. Terya Chamore, who had been spying on the Thalmor, was the next most senior member and so, was made the Master of the Oculus; allegedly, Chamore had been escorted to the last Imperial bastion by Thalmor soldiers, but few reports verified this.
For several years, the Oculus dealt with unrest in the Empire, helping to consolidate Mede's rule in the provinces. By 4E 29, the Oculus had grown into a large organization and had success in governing Morrowind and several other at risk provinces, but they had gone blind to the threat of the Thalmor; sympathizers of the movement in Valenwood launched a coup d'etat and ended Imperial rule of the Bosmer homeland.
However, the Empire would not let Valenwood fall without a fight. Imperial legions, Bosmeri auxillaries, and the Oculus fought the Thalmor sympathizers, bound to win until Altmer armies landed in the province. The Empire was swept out of Valenwood by the might of the elven armies from Alinor. Valenwood and Alinor formed the Third Aldmeri Dominion soon after. After several weeks of guerilla warfare, the final remnants of the Oculus in Valenwood were discovered and killed as they were hatching an elaborate plot to assassinate the new Altmeri and Bosmeri governors of the region.
After this, Terya Chamore was arrested and put on trial for treason when the Blades uncovered evidence of Terya's relation to the Thalmor. Chamore was executed in the Imperial City in 4E 30, after a short trial. Martin Valens, a Legate in the Imperial Legion, became the new Master of the Oculus. His ambitions led to the Oculus becoming extremely powerful in the political world. A branch of the Oculus, the Penitus Oculatus, was even created as bodyguards of the Emperor when the Blades relinquished their ancient right to guard Tamriel's emperor.
By 4E 50, Martin Valens was one of the most powerful men in the Empire. He had ascended to Commander of the Legions, Master of the Oculus, and Commander of the Penitus Oculatus. He had even become a Knight Commander of the Order of the Dragon and Knights of the Nine.
Valens had earned these ranks and titles by honor and glory, not by lying and deceit. He was an actual patriot of the Empire, and wished to see the Empire restored to what it once was. The Emperor, however, did not see it that way. The Oculus had gained too much power in his eyes, and so, after lots of pressure from certain members of the Council and the Blades Grandmaster, the Emperor ordered the Blades to assassinate Valens and destroy the Oculus.
The Blades glady followed their emperor's orders. On a dark night in 4E 50, on Sun's Dusk, Valens was killed as he returned to his estate outside of Chorrol. The Oculus's commanding officers were also killed. The Blades quickly moved through the Oculus's ranks after capturing various documents of the rival organization. In 4E 51, the Oculus was destroyed, its remaining members fleeing across Tamriel for safety.
The Emperor then ordered damnatio memoraie on the Oculus. The once powerful spies were ended after only fifty-one years of existence.