 The situation was so dire that Manuel left Constantinople to travel around Western Europe asking for further aid against the Ottomans, visiting Italy, France and England.Ultimately, the siege was resolved peacefully by Manuel through signing a peace treaty with Bayezid's son and successor, Mehmed I, in 1403, which among other things returned the city of Thessaloniki, captured by the Ottomans in 1387, to Byzantine rule.There was peace between the Palaiologans and the Ottomans until 1421, when Mehmed I died and Manuel retired from state affairs, to pursue scholary and religious interests.