Murad II was generally described as a ruler who preferred peace to war. Commenting on him, the Byzantine historian, Ducas, remarked that he cared for the benefit of the common people and had sympathy for his poor subjects, whether Muslims or dhimmis. Not seeking the complete destruction of a defeated nation, Murad used to negotiate a treaty with the enemy, as soon as the latter sought peace. The terms were usually to accept the enemy as a vassal who continued to rule over his own territory. In following this policy, Murad enjoyed the support of a group of high officials who wanted a state modelled according to Islamic tradition, such as Egypt or Persia, and having an economy based on trade, crafts and agriculture. The leader of this group was the vizier, Halil Djandarli, also known by the nickname ‘companion of the infidel’ (giaur ortagi), a name clearly invented by his belligerent opponents. On the other hand, Murad’s milieu included persons strongly in favour of the ideal of holy war or the policy of conquest. Another of his viziers, Fazlullah, was a notorious war-monger, criticising the sultan for showing benevolent tolerance towards the infidel instead of treating them according to God’s will by using his sword.
The moderate party was encouraged by important economic development achieved during the years of relative peace preceding and following Murad II’s accession. Trade began to thrive and several Ottoman cities, such as Bursa, with its important silk market, expanded considerably. Venetian, Genoese and Ragusan merchants frequented Ottoman territories, while relations established between the sultan and the duke of Milan opened new trade outlets to Italy. The townspeople prospered. When Ottoman troops besieged Constantinople, they were accompanied by numerous merchants, including money changers and perfume and shoe sellers, who had come from Turkish towns to buy items which would be pillaged by the soldiers.
In 1427 an old-time vassal, the knez of Serbia, Stephan Lazarevic, died. Both Ottomans and Hungarians intervened in Serbia, and a long period of war between the two states began. King Sigismund of Hungary, determined to fight the Turk, was encouraged by the Venetians. The latter occupied Thessalonica in 1423 but, unable to defend it against frequent Turkish raids, they therefore proposed joint action to the king. Together they sought allies in the east by making contacts with the lord of Mesopotamia, Osman Karayuluk, and the emir of Karaman, both of whom enjoyed the support of Timur’s successor, Shahrukh, established in Herat. In spite of this the Ottomans were to expel the Venetians from Thessalonica in 1430. In the same year they peacefully annexed the important cities of Yanina and Arta, possessions of the short-lived petty dynasty of the Tocco. The conflict with the Karamanoglu and Karayuluk was more serious as their patron, Shahrukh, exercised pressure upon the sultan by demanding the yearly tribute imposed by Timur after the battle of Ankara. Murad convinced him that he should be exempted because he carried out holy war. Once, when ambassadors of Shahrukh visited Edirne, they were shown Hungarian prisoners and were offered 300 of them as a gift to their lord.
In 1437 the Ottomans again took the offensive in the Balkans: Sigismund of Hungary died, while Fazlullah took over the office of vizier and the war party strengthened its position. The Byzantine emperor, in an effort to save his crumbling state, decided to participate in the Council of Ferrara aimed at the union of the Greek Orthodox with the Roman Church. He met with the strong disapproval of the sultan who was afraid of the possibility of a crusade. When the Byzantine emperor finally sailed to Italy, Murad was incited by his high officials to proceed to an attack against Constantinople, but he was dissuaded by Halil Djandarli.
Unable to expel the Hungarians from Belgrade, the Ottomans were compensated by the conquest of the important silver mines of Novobrdo in 1439, and two years later they captured the town as well. The war continued, their opponents being led by a promising military commander, Janos Hunyadi, voivode of Transylvania. Pope Eugenius IV began to preach the crusade shortly after the signing of the Union of the Churches (1439), in spite of its outright rejection by the Byzantine people. The crusaders marched under the orders of Hunyadi and of the young king of Poland and Hungary, while the Karamanoglu raided the Ottoman territories in Anatolia. The sultan confronted the Christian army between Nis and Sofia in full winter. He was defeated and obliged to conclude a ten-year peace with the Christians (Treaty of Edirne-Szegedin 1444).
According to Islamic judicial principles, a truce with the infidel should not last for more than four months or, at the most, one year. Only if the Muslim party really needed to recover might a truce be made for ten years. It may be assumed that the sultan was in a difficult position, and the war party in his court highly critical. On the other hand, the sultan’s vassals began to revolt, especially in Albania, the Morea and the territories of Karaman. Murad imposed order but, immediately afterwards, he announced his abdication in favour of his son, Mehemmed, then a youth twelve years old. Murad probably took this decision because he had failed in the war and lacked the support of all his high military officials. Signs of social unrest were also visible: in Edirne, a Muslim holy man, preaching heretical views, was sentenced to death, together with his followers.
On the other hand, the Christians overestimated the victories over the Turks, and a few weeks after the treaty they launched a new crusade. Murad took the lead of the army and crushed the Christians at the battle of Varna in which the young king, Wladyslaw, was killed (10 November 1444). A couple of years later Murad II was brought back to the throne after a coup d’etat organised by Halil Djandarli. He continued the struggle against Hunyadi, whom he defeated once again at Kosovo (1448), while his fleet threatened Constantinople and unsuccessfully attacked Kelli, at the mouth of the Danube. He finally died in 1451.