On 14 June 1256, a treaty was signed between the Lombard triarchs and Gradenigo at Thebes, the chief residence of Guy I de la Roche. The triarchs repudiated their vassalage to Achaea and declared themselves lieges of the Commune of Venice, as token of which they would send an annual gift of cloths of gold to Venice, one each for the Doge and St. Mark's Cathedral, and hold festive liturgies in Venice's honour at Christmas, Easter, and the feast-day of St. Mark. The previous agreements of 1209 and 1216 were renewed, but, while the triarchs and their domains were freed from any duties and the considerable tribute that they paid to Venice until then, they in turn gave up the rights to all customs revenue to the Republic. Venice also received further concessions, such as the right to regulate the weights, measures and scales for all Euboea, and privileges for its citizens. More importantly, the triarchs ceded to the Republic full possession of the strategic citadel that guarded the bridge over the Euripus Strait, and of extensive properties in the city of Negroponte itself. This marked the establishment of a separate Venetian colony in Negroponte, and began the long and gradual process whereby the entirety of the city and island of Negroponte would pass under Venetian rule.