 A week after that , Theoktistos and Sergios Niketiates were sent on a campaign to recover Crete , which had been conquered in the 820s by Andalusian exiles . The expedition at first went well , as the Byzantine army landed and took control over most of the island , confining the Andalusians to their capital , Chandax . At this juncture , Theoktistos heard a rumour that in his absence , Theodora intended to raise her brother Bardas to the imperial throne . He hastily abandoned the army under Niketiates and returned to Constantinople , only to find the rumours false . Once in Constantinople , news arrived of an invasion of Asia Minor by Umar al @-@ Aqta , emir of Malatya . Theoktistos was sent at the head of an army to confront him , but the resulting Battle of Mauropotamos ended in a Byzantine defeat . At the same time , the expeditionary corps left in Crete was defeated and almost annihilated by the Andalusians , who killed Niketiates . 
