William Miles' codex

William Miles' Codex is a codex written by William Miles, the leader of the Assassin Order until his retirement in 2013, detailing the knowledge he gained during his life as an Assassin.

After his son Desmond died on 21 December 2012 to prevent the coronal mass ejection from destroying the Earth, William Miles' mourning led him to abandoning the Order and living as a hermit for several months, writing his experiences and knowledge down in a journal. In May 2013, William sent the codex to Gavin, whom he appointed as his successor as leader.

Reference

 * Assassin's Creed: Initiates