Abbasid invasion of Asia Minor
... that during the Abbasid invasion of Asia Minor of 782 CE, Byzantine general Tatzates defected to the Arab side when the Byzantines already had the Abbasids surrounded and asking for negotiations?
... that during the <b id="mwEDc"><a href="./Abbasid_invasion_of_Asia_Minor_(782)" id="mwEDg" rel="mw:WikiLink" title="Abbasid invasion of Asia Minor (782)">Abbasid invasion of Asia Minor</a></b> of <span about="#mwt56" class="nowrap" data-mw='{"parts":[{"template":{"target":{"wt":"Nowrap","href":"./Template:Nowrap"},"params":{"1":{"wt":"782 CE"}},"i":0}}]}' id="mwEDk" typeof="mw:Transclusion">782 CE</span>, <a href="./Byzantine_Empire" id="mwEDo" rel="mw:WikiLink" title="Byzantine Empire">Byzantine</a> general <a href="./Tatzates" id="mwEDs" rel="mw:WikiLink" title="Tatzates">Tatzates</a> defected to the Arab side when the Byzantines already had the <a class="mw-redirect" href="./Abbassid_Caliphate" id="mwEDw" rel="mw:WikiLink" title="Abbassid Caliphate">Abbasids</a> surrounded and asking for negotiations?