The Fatimids adopted Green ("akhdar") as the colour of their standard, which symbolized their allegiance to Ali, who, in order to thwart an assassination attempt on Muhammad, once wrapped himself in a green coverlet to appear to be Muhammad. When Hassan I Sabbah captured Alamut, it is said he hoisted the green standard over the fortress, it was later reported that Hassan I Sabbah prophesied that when the Hidden Imam made himself known he would hoist a red flag, which Hasan II did during his appearance. Following the destruction of Alamut, Isma'ili hoisted both green and red flags above the tombs of their Imams. Green and Red were combined in the 19th century Isma'ili flag known as "My Flag".