Operation: Phoenix was an organised attack by Zamorakian wizards against the first Wizards' Tower. The battle took place in the Year 70 of the Fifth Age, and ultimately resulted in the complete destruction of the tower and the loss of many magical secrets, including that of runecrafting. The event, though referenced frequently throughout RuneScape's history and dialogue, has been referred to by name only once, in a Temple Knight commorb dossier obtained during the Wanted! quest.
Details regarding the battle itself are few. Prior to the attack, Zamorakians had largely been tolerated, if not fully accepted, by most within nations such as Misthalin and Asgarnia. Many had worked in the Wizards' Tower itself. For reasons that are not completely clear, these Zamorakian mages betrayed the Wizards' Tower and, in the process, burned in to the ground. Many of the secrets of magic and runecrafting were lost as a result.
Following Operation: Phoenix, anti-Zamorakian sentiment was strong throughout the human kingdoms. Many Zamorakians, such as the Dagon'hai in Varrock, were persecuted and forced into hiding. Although this sentiment still exists today, it has diminished to a degree. The Wizards' Tower was later rebuilt, albeit on a smaller scale. The modern Zamorak Magical Institute is believed by the Temple Knights to be descended from the Zamorakian mages originally responsible for the plot.