if he were truly the Pope's servant, as he claimed in his letters, he should allow the Latin Archbishop of Dyrrhachium access to the estates owned by the archbishopric in Michael's domains—but it did serve for the moment to earn Michael the Pope's goodwill, as well as precious time. According to Loenertz, it also appears that at some point Michael had paid homage to the Kingdom of Thessalonica as its vassal. 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. In summer 1209, after the Latin Emperor Henry of Flanders () quelled a revolt of the Lombard barons of Thessalonica and brought the Kingdom of Thessalonica under his effective control, Michael sent envoys to propose an alliance. Henry distrusted Michael's sincerity, but sent an embassy to Epirus with his terms, which amounted to Michael declaring himself a vassal of the Latin Empire. Michael was able to sidestep an outright declaration of submission by offering the hand of his eldest daughter to the Emperor's brother, Eustace, and a third of his lands as her dowry. Henry accepted, and the peace agreement was sealed with the marriage of Eustace and Michael's daughter. Finally, in early 1210, Michael's envoys, the Bishop of Tzernikon Theodore and Symeon Kounales, met with the Venetian duke of Dyrrhachium, Marino Vallaresso, and negotiated a treaty, confirmed by oath on 20 June. Thereby Michael accepted to become a vassal of Venice, holding his lands