Great Purge

The Fall of the Assassin Order began in 2000, when Daniel Cross unwillingly assassinated The Mentor, leader of the Assassin Order. This left the Assassins vulnerable as the Mentor would oversee and coordinate the actions of the order. absergo also gained information on every Assassin training camp in the world, causing a global evacuation of every compound.

The Abduction
When Daniel was very young he was abducted by Abstergo Industries, who performed anaesthetised surgery on him, exploring his memories and burying within him, somehow, an impulse that would force him to kill the leader of the Assassins as soon as he has the chance.