The Treaty of Gallipoli, concluded in January or early February 1403, was a peace treaty between Süleyman Çelebi, ruler of the Ottoman territories in the Balkans, and the main Christian regional powers: the Byzantine Empire, the Republic of Venice, the Republic of Genoa, the Knights Hospitaller, and the Duchy of Naxos. Concluded in the aftermath of the Battle of Ankara, while Süleyman tried to strengthen his own position in the succession struggle with his brothers, the treaty brought major concessions to the Christian states, especially the Byzantines, who regained lost territories and achieved a position of nominal superiority over the Ottoman ruler. Its provisions were honoured by Süleyman as well as by Mehmed I, the victor of the Ottoman succession struggle, but collapsed after Mehmed’s death in 1421.
On 26 July 1402, in the Battle of Ankara, the OttomanSultanBayezid I was defeated and captured by the Turco-Mongol warlord Timur. This momentous event overturned the balance of power in the region, as the Ottoman domains in Anatolia were divided by Timur, who restored many of the independent Turkish beyliks previously absorbed by Bayezid. Timur did not interfere with the Balkans, where the Ottoman conquest was also far advanced: before Ankara, Constantinople, almost the last remnant of the Byzantine Empire, was cut off and on the verge of falling to Bayezid. As in Anatolia, the sudden collapse of Ottoman power left a power vacuum, in which the various Christian powers of the region—the Byzantines, the Hungarians, the Republic of Venice, and a number of minor rulers—each tried to secure their interests as best possible, while being too weak to actually challenge Ottoman power.
Süleyman Çelebi, the eldest son of Bayezid, escaped the disaster at Ankara and arrived at Gallipoli on 20 August. While his other brothers were left in Anatolia to deal with Timur and try to salvage what domains they could, Süleyman claimed control over the Ottoman territories in the Balkans (“Rumelia“). His position there was insecure, however, and his first priority was to contact the Christian powers of the region and arrange a truce with them, especially in view of the necessity to one day return to Anatolia and contend with his brothers and other rivals (cf. Ottoman Interregnum). Already on 22 September, the Venetian Senate was discussing the matter, and hoped to gain control over Gallipoli. The Venetians also contacted the Byzantine emperorManuel II Palaiologos, who at the time was in Paris on a grand journey seeking help in the West, urging him to return home, since Manuel’s nephew and regent, John VII Palaiologos, was known to sympathize with Venice’s maritime and commercial rivals, the Republic of Genoa.
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. The Venetians, who among other concerns wanted to use Ottoman influence to settle their rivalry with the FlorentineAntonio I Acciaioli, who had captured Athens, sent their most experienced diplomat, the lord of Andros, Pietro Zeno, as their negotiator, along with Marco Grimani, while Genoa named Jean de Chateaumorand as its envoy to the eastern potentates.