The event that triggered the internecine fighting was an attack on the al-'Askari Shrine in al-Samarra' that destroyed the golden dome of the mosque. An AQI attack the next year destroyed the two 100-feet tall minarets at the shrine. The shrine is the burial place of the 10th and 11th Shi'a imams and considered one of the holiest sites in Shi'a Islam. (It has since been restored.)