Treaty of Viterbo

Charles was to be confirmed in possession of Corfu and some cities in Albania, once the dowry of Helena of Epirus, and was to be given suzerainty over the Principality of Achaea and Baldwin's rights upon the Aegean islands, excepting Lesbos, Chios, Samos and Kos.

The treaty placed a heavy burden on Baldwin in forcing him to surrender his rights over Achaea (to which the Duchy of Athens was also subject), as it represented the richest part of his empire still in Frankish hands.

Nonetheless, the growing power of Charles represented Baldwin's best chance to recover Constantinople, although had the crusade gone forth as planned, he would probably have found himself more ruled than ruler in the presence of Angevin arms.

In the event, the launch of the Eighth Crusade delayed any expedition against Constantinople, and Michael VIII Palaeologus, by keeping afoot the project of unifying Greek and Latin Churches, had it put off until 1280.

At the eleventh hour, the Sicilian Vespers put an end to all plans for the long-delayed crusade by burning the invasion fleet in Messina harbor.