Great Purge

"The Great Purge" referred to an Abstergo Industries operation, with the intent to ensure the global eradication of the Assassin Order. After Daniel Cross, a Templar sleeper agent who had infiltrated the Order, was allowed to meet the Mentor of the Assassins, he acted upon an impulse implanted into his brain by Abstergo to kill the Mentor.

Successful in his objective, Daniel returned to Abstergo's Philadelphia facility and revealed the locations of all the Assassin camps he had come into contact with over the previous two years, after which Abstergo initiated "The Great Purge;" the elimination of this global network of camps. While mostly successful in his goals, Daniel had not visited a number of camps, allowing them to remain unscathed. The few remaining Assassins were forced into hiding, and from then on, they began operating in small cells.

Abduction
"Я хочу домой." ("I want to go home" in Russian.)"

- A young Daniel Cross, c. 1985.

In September 1985, a young American boy was abducted by the Lineage Discovery and Acquisition division of Abstergo Industries, and became a test subject known as Subject 4; later codenamed Daniel Cross. Using a working prototype capable of mimicking a Piece of Eden, a subliminal impulse was implanted into Subject 4's brain that would force him to subconsciously infiltrate the Assassin Order and kill the Order's Mentor once the opportunity to do so had arisen.

Once Abstergo was finished experimenting, Daniel was sent into the outside world in his underwear. He was picked up by a man named Luke and his female partner, who noticed the young boy while driving in their truck. After the woman called out to Daniel, he only replied in Russian; after having been experimented upon, Cross had been suffering from the bleeding effect and was reliving the memories of his Russian ancestor, the Assassin Nikolai Orelov.

Infiltrating the Order
"I just beat the shit out of two guys like it was nothing, my vision went red and something took over, pure instinct [...] It feels like there's something coiled like a snake deep inside of me, and it's waiting to get out..."

- Daniel Cross.

Years later, after experiencing hallucinations and attempting to kill a civilian because he believed the man was a Templar, Daniel was kidnapped by a woman known as Hannah Mueller, who mistook him to be an Assassin like herself. He woke up the next day in an Assassin camp, and Hannah and Daniel met with Paul Bellamy, the director of the camp, who explained to Daniel that there was no record of him, and told the man that his tattoo on his arm was the Assassins' insignia, to Daniel's surprise. When attempting to leave after a question about Tunguska, Daniel was stopped by two Assassins who had been watching the exchange. He easily bested them, but was inevitably stopped by Bellamy, who had put his Hidden Blade to Daniel's neck.

Hannah's attention was drawn to Daniel that night due to Daniel's fit of rage, overturning all of the nearby furniture. Daniel explained to Hannah about his medication and told her that he needed it back. At first, Hannah was reluctant but Daniel eventually convinced her to help him. After discovering that Daniel had thrown the last of his medication out, the man fell into a moment of depression, to which Hannah told Daniel that whatever was inside his mind, he should let it out.

Search for the Mentor
"Hannah... it's okay... I saw everything... I saw the shape of time. I know my purpose, I understand what I have to do... I have to find the Mentor."

- Daniel Cross, after his hallucination.

Daniel and Hannah discussed the roles of Assassins in the contemporary Assassin Order after his moment of depression, with Hannah mentioning that she would like to know more about his hallucinations. During this time, Cross unexpectedly marked the window with a symbol much like a Staff of Eden and asked her what it meant.

Soon after, Paul Bellamy burst into Daniel's flat and claimed that there was a survivor of a mission to Tunguska in 1908, Nikolai Orelov, who eventually went to America. Cross was overwhelmed by hallucinations brought on by the name and punched Bellamy, when he demanded to know what he was seeing.

The terror brought on by the images caused Daniel to flee over the rooftops, still assaulted by the visions as he was pursued by Bellamy and Hannah. The hallucinations grew stronger until he finally collapsed from the strain. Daniel's first words after his collapse were that he knew his purpose; he was meant to find the Mentor.

Assassination of the Mentor
"Cross. Your name will be Daniel Cross. Climb their ranks until you can go no higher - and STRIKE."

- Warren Vidic to Daniel Cross, during the implantation of the impulse in his brain.

After two years of searching for the Mentor, Cross sought help from other Assassins around the globe, and one night on November 5th of 2000, two men came into Daniel's apartment and kidnapped him. Daniel woke up to find himself in Dubai, where he finally met the Mentor. The Mentor told him that he had heard of Daniel's visions, and believed that he would be of very unique value.

The Mentor then explained to Daniel how the Assassins had come a long way from murdering those who had become too powerful, greedy or both. He also implied that he would choose Daniel as his successor and presented Daniel his own Hidden Blade, telling him that he had "earned it" and fully initiated him into the Assassin Order. As soon as he put it on, Daniel felt as if he was made to wear and use it, though suddenly, Daniel recalled his memories from Abstergo, being experimented upon by Warren Vidic, and having the impulse to kill the Mentor buried deep within him. In this split second, which he hadn't realized until the time had come, he recalled Bellamy and Hannah telling him to unleash whatever was inside of him and of being given a new name; Daniel Cross. Acting on the impulse, Daniel assassinated the Mentor and escaped the facility in a panic stricken state.

Eradication of the Assassin camps
"With the information retrieved from Cross, we now may mobilize tactical teams to initiate strikes on Assassin compounds globally."

- Warren Vidic in an email to Alan Rikkin.

Daniel made his way to Abstergo's research facility in Philadelphia, where he requested to be put in the Animus, so that he could "be with his family." Some time later, Daniel was tied to an operation chair and unwillingly drugged by doctor Sung into revealing the location of the Assassin camps and safehouses he had visited during his journey, allowing the Templars to initiate "The Great Purge." Nearly all Assassins within their camps, including children, were massacred by military agents under order of Abstergo Industries, with only few Assassins managing to evacuate, and with a few off-the-grid settlements remaining unscathed.

The operation was a victory for the Templars, and the Assassins were unable to recover from their defeat, remaining under the radar and operating in teams of four. The death of the Mentor also allowed the Templars to be successful in placing their puppet, George W. Bush, as President of the United States of America.