Stephen was the youngest of the four sons of Andronikos Asen Zaccaria, Grand Constable of Achaea and Baron of Chalandritsa and Arcadia.
[4][5] In 1408 Stephen, threatened by mounting Ottoman raids in the Peloponnese and faced with financial difficulties, decided to lease the administration of Patras to the Republic of Venice for five years, in exchange for an annual fee of 1,000 ducats.
This move suited the strategic interests of the Republic, as together with Lepanto, Patras gave it control of the entrance to the Corinthian Gulf.
[7] Faced with renewed offensives by the Byzantines, in early 1422, both Centurione and Stephen contacted the Knights Hospitaller, offering to surrender their domains to them, but the Hospitallers refused to become involved, citing their commitments against the Ottomans in the southeastern Aegean.
[8] Venice then tried to intervene and buy the entire Peloponnese from the various local rulers, or at least organize an effective league against the Ottoman threat, but the negotiations in 1422–23 failed to achieve any result.