Fourth Fitna
... that the Fourth Fitna pitted two half-brothers, the Abbasid caliphs al-Amin and al-Ma'mun, against each other?
... that the <b id="mwC7c"><a href="./Fourth_Fitna" id="mwC7g" rel="mw:WikiLink" title="Fourth Fitna">Fourth Fitna</a></b> pitted two half-brothers, the <a href="./Abbasid_Caliphate" id="mwC7k" rel="mw:WikiLink" title="Abbasid Caliphate">Abbasid caliphs</a> <a href="./Al-Amin" id="mwC7o" rel="mw:WikiLink" title="Al-Amin">al-Amin</a> and <a href="./Al-Ma'mun" id="mwC7s" rel="mw:WikiLink" title="Al-Ma'mun">al-Ma'mun</a>, against each other?