Theodore Komnenos Doukas
Despite these diplomatic manoeuvrings, according to a series of letters of Innocent III dated to autumn 1210, Michael engaged in combat with the Prince of Achaea Geoffrey I of Villehardouin () and his barons; the letters do not give any further details. Modern researchers have linked this reference either with his supposed leadership in the battle of Kountouras, or, more plausibly, with an abortive campaign in the Peloponnese sometime in 1207–09 in order to aid the beleaguered ruler of Argos and Corinth, Leo Sgouros, who was being besieged by the Crusaders in his citadel on the Acrocorinth. Traditionally, several scholars, such as Karl Hopf and Antoine Bon, have furthermore identified a certain Theodore, who appears as "lord of Argos" and Sgouros' successor in leading the resistance against the Crusaders, with Michael's half-brother Theodore Komnenos Doukas. Loenertz points out, however, that not only is there no evidence for such an assumption, but that Theodore Komnenos Doukas is known to have been in the service of the Nicaean emperor, Theodore I Laskaris (), at the time.