Negotiations soon began, and Süleyman sent envoys both to Venice and Manuel, offering significant concessions. Manuel, however, would not return to Constantinople until 9 June 1403, and an agreement was reached during his absence, after negotiations lasting three and a half months.[6] The Venetians, who among other concerns wanted to use Ottoman influence to settle their rivalry with the Florentine Antonio I Acciaioli, who had captured Athens, sent their most experienced diplomat, the lord of Andros, Pietro Zeno, as their negotiator, along with Marco Grimani,[7][8] while Genoa named Jean de Chateaumorand as its envoy to the eastern potentates.[6]