Moldavia into "some kind of fortress," and from there, to launch attacks against Poland and Hungary. The Ottomans also feared the strategic position of Moldavia, whence it would only take 15 to 20 days to reach Constantinople. In 1448, Petru II of Moldavia awarded Chilia to John Hunyadi, the governor of Transylvania;, effectively ceding control of the strategic area on the Danube, with access to the Black Sea, to Hungary. With the assassination of Bogdan II of Moldavia in 1451 by his brother Petru Aron, the country fell into civil war as two pretenders fought for the throne: Aron and Alexăndrel. Bogdan's son, Stephen, fled Moldavia together with his cousin, Vlad Dracula — who had sought protection at the Moldavian court – to Transylvania, at the court of Hunyadi. Even though Hungary had made peace with the Turks in 1451, Hunyadi wanted to transform Wallachia and Moldavia into a barrier that would protect the kingdom from Ottoman expansion. In the fall of 1453, after the Ottoman capture of Constantinople, Moldavia received an ultimatum to start paying tribute to the Porte; two years later, on 5 October 1455, Aron sent the first Moldavian tribute to the Porte: a payment of 2,000 ducats. With both Wallachia and Moldavia conducting a pro-Ottoman policy, the plan to install Vlad Țepeș as prince of Wallachia began to take shape. Sometime between April to July 1456, with the support of a few Hungarian troops and Wallachian boyars, Prince Vladislav II was dethroned and slain, as Vlad Țepeș took possession of the Wallachian throne; and as such, Chilia became a shared Wallachian-Hungarian possession. In April 1457, Vlad Țepeș supported Stephen with 6,000 horsemen, which the latter used to invade Moldavia and occupy the Moldavian throne, ending the civil war as Aron fled to Poland. The new prince continued sending the tribute that his uncle and Mehmed had agreed upon, and in such way, avoided any premature confrontation with his enemy. His first priority was to strengthen the country and to retrieve its lost territory. Because Aron resided in Poland, Stephen made a few incursions in southern Poland. The hostilities ended on 4 April 1459, when in a new treaty between the two countries, Moldavia accepted vassalage and Poland returned Hotin back to Moldavia; the latter also assumed the obligation to support Moldavia in retrieving Chilia and Cetatea Albă. It was also in the interest of Poland to