Battle of Siffin
Through his forename, al-Baghdadi was rumored to have been styling himself after the first caliph, Abu Bakr, who led the "Rightly Guided" or Rashidun. According to Sunni tradition, Abu Bakr replaced Muhammad as prayer leader when he was suffering from illnesses. Another feature of the original Rashidun was what some historians dub as the first Sunni–Shia discord during the Battle of Siffin. Some publishers have drawn a correlation between those ancient events and modern Salafizing and caliphizing aims under al-Baghdadi's rule.