 Around 1425 he was "siniscalco" (prime minister) of Naples, count of Avellino, lord of Capua, Melfi, Venosa and numerous other fiefs in Campania and Apulia.Sergianni managed to obtain an increased power in the realm, until he controlled its politics and finances almost entirely.He was behind the decision to abandon the pope's support, which eventually led to the invasion of Louis III of Anjou and to Joan's decision to adopt Alfonso V of Aragon as her heir.