Alexander was a complete idiot. For some reason, probably jealousy, he hated his brother Leo VI. While Leo did his best to run the empire Alexander spent all his time living the good life. Friction between the two escalated to the point where Leo had him stripped of his associate emperor status and then left him to drink himself to death.
But he didn't.
Leo's son was still much too young and no one else had a weightier claim to the throne at the time of Leo's death. So Alexander was crowned emperor and then went on a crazy spree to erase Leo's memory inflamed by nothing but hatred and revenge. And since Leo was a conscientious ruler the revoking of every treaty signed under him had predictably disastrous consequences. The gravest of these was upsetting the delicate truce achieved with the Bulgars who had come to expect an annual tribute. Alexander waved off the diplomats sent to renew the treaty with some choice insults and this precipated a large-scale war with them.
The leader of the Bulgars, Symeon, assembled a huge army and headed on the warpath to Constantinople. Before matters got really ugly the world was relieved to hear Alexander had dropped dead from a stroke.
SB 1737 Solidus Obv: +IhSXRSReXReGNAntIYm - Christ enthroned facing, wearing pallium and colobium, raising hand in blessing and holding the book of Gospels in left.
Rev: +ALeXAndROSAYGYStOSROm' - Alexander standing facing, wearing crown and loros and holding globus cruciger, crowned by St. Alexander, on right, wearing pallium and colobium, and holding cross.