130,000 according to numerous sources, including the Ottoman historian Şükrullah who, in the 1460s, gives the figure of the crusader army as 130,000 in his Behçetu't-Tevârih. Composition of Ottoman forces The strength of the Ottoman forces is also estimated at 15–20,000; but inflated figures are common here as well. Numerous sources provide estimates of the size of the army as up to 60,000 including the Ottoman historian Şükrullah, who, writing in the 1460s, gives the figure of the Ottoman army as 60,000 in his Behçetu't-Tevârih; alternately described as roughly half of the Crusader army. The Ottoman force also included 1,500 Serbian heavy cavalry knights under the command of Prince Stefan Lazarević, who was Sultan Bayezid's brother-in-law and vassal since the Battle of Kosovo in 1389. Journey While Philip, Duke of Burgundy, had originally planned to lead the crusade along with John of Gaunt and Louis of Orleans, all three withdrew, claiming that the peace negotiations with England required their presence, though perhaps also because none dared leave the vicinity of the throne if their chief rivals stayed. However, Burgundy retained control of the enterprise he was funding by naming 24-year-old John, Count of Nevers, the Duke's eldest son, for nominal command. Burgundy, perhaps recognizing that his son, as well as Constable d'Eu and Marshal Boucicaut, who were both under 35, lacked the necessary experience, summoned Enguerrand VII, Lord of Coucy, the most experienced warrior and statesman of the realm, and prevailed on him to be "chief counselor" to Nevers during the crusade. The ambiguity of the crusaders' command structure would prove to be crucial in the outcome. While Nevers was given a long list of "counselors", as well as another list of prominent French lords on the crusade with whom Nevers could consult "when it seemed good to him", the concept of unity of command was not yet embraced by medieval warriors. Rules of discipline for the crusade were decreed at a War Council on 28 March 1396, which included the final provision, "Item, that [in battle] the Count and his company claim the avante garde," revealing that the chivalric code continued to require knights to prove their valor by leading the charge. To Buda The crusade set forth from Dijon on 30 April 1396, heading across Bavaria by way of Strasbourg to the upper Danube, from where they used river transport to join with Sigismund in Buda. From there