 It is possible that during this campaign, Henry was assisted by his vassals from Achaea, thereby explaining the reference in the Pope's correspondence of Achaean barons fighting against Michael, rather than assuming an Epirote expedition to the Peloponnese.The Latin Emperor wrested lands from both allies, but was forced to cut short his campaign and return to Constantinople, which was being threatened by the Bulgarian emperor Boril.Henry left Thessalonica in the charge of his brother Eustace and of Berthold of Katzenelnbogen, who then defeated another invasion by Strez, supported with troops from his brother Boril.