Two years after his accession Mahommed overcame a rebellion of the prince of Karamania and recaptured his stronghold Konia (1416), and then, turning northwards, forced Mircea, voivode of Walachia, who in the dispute as to the succession had supported Prince Mussa, to pay tribute.
Peace was also made at the same time with the despot of Servia and the voivode of Walachia, on the basis of the payment of tribute.
In Transylvania, however, the common peril evoked by the Turkish incursion and a simultaneous rising of the Vlach peasantry had knit together the jarring interests of Magyars, Saxons and Szeklers, a union which, under the national hero, the voivode Janos Hunyadi, was destined for a while to turn the tide of war.
The pope urged the king of Hungary to take advantage of this favourable opportunity by breaking the truce solemnly agreed upon, and nineteen days after it had been concluded a coalition was formed against the Turks; a large army headed by Ladislaus I., king of Hungary, Hunyadi, voivode of Walachia, and Cardinal Cesarini crossed the Danube and reached Varna, where they hoped to be joined by the Greek emperor.
This desolate region was subsequently peopled by Vlachs, whom the religious persecutions of Louis the Great had driven thither from other parts of his domains, and, between 1350 and 1360, their voivode Bogdan threw off the Hungarian yoke altogether.