[3] His brother Carlo I gave the island of Zakynthos to him as an appanage in 1399, and Leonardo also received lands in the Principality of Achaea by Prince Pedro de San Superano.
[2] In 1407, Leonardo attacked the new Prince of Achaea, Centurione II Zaccaria, who had seized his fiefs in the Morea in 1404, and conquered Glarentza, the principality's main town.
Leonardo campaigned against Zaccaria in 1413, but in summer 1414, he was sent by Carlo to Corinth, where the Byzantine emperor Manuel II Palaiologos supervised repairs to the Hexamilion wall.
The emperor awarded Leonardo with the high court dignity of megas konostaulos, but enjoined both brothers to seek peace with Zaccaria.
The brothers appealed to Venice, and with her mediation concluded three-year truce was agreed which left Glarentza once again under Achaean control.