Treaty of Sapienza

The Treaty of Sapienza was concluded in June 1209 between the Republic of Venice and the newly established Principality of Achaea, under Prince Geoffrey I of Villehardouin, concerning the partition of the Peloponnese (Morea) peninsula, conquered following the Fourth Crusade.

By its terms, Venice, which had been accorded most of the Peloponnese in the Partitio Romaniae, recognized Villehardouin in possession of the entire peninsula except for the two forts of Modon and Coron, which came under Venetian control, and secured commercial and tax privileges in the Principality.

Isolated fortresses like Monemvasia, or the inhabitants of the mountainous regions of Tsakonia and Taygetus, still resisted, but by the end of 1205, Champlitte had consolidated his position enough for Pope Innocent III to refer to him as "Prince of Achaea".

It was probably there—and likely through the Emperor's mediation—that negotiations began to reach a settlement reconciling Villehardouin's de facto possession of the Peloponnese and the Venetian claims, which led to the signing of a treaty at the island of Sapienza, off Modon, in June.

As the French medievalist Antoine Bon remarks, other, later sources, chiefly the Chronicle of the Morea, present the feudal organization of the principality as "complete and definitive" by 1209/10, but the Treaty of Sapienza shows the process of its consolidation still ongoing and incomplete.