Serbian Despot Đurađ Branković fled to Hungary to seek support for the defense of his realm, organized by his son Grgur.

During the siege of Smederevo (the Despotate's capital city) in 1439, Murad II ordered the marcher-lord Ishak-Beg, who was returning from Mecca, to join forces with Hadım Şehabeddin and besiege Novo Brdo.

[6] The Ottomans captured Smederevo on 18 August 1439, reducing the territory of the Serbian Despotate to Zeta and a region around Novo Brdo.

The Ottomans realized that it would be difficult to capture the well-defended Novo Brdo, so Murad II ordered for retreat and a stay in Skopje during the winter.

[15] Despot Đurađ Branković and his wife traveled from Hungary to Zeta, accompanied with several hundred cavalry and Albanian vojvoda Petar Spani.

[17] Then Branković arrived at Ragusa (Dubrovnik) at the end of July 1440 and after several days he continued his journey toward his coastal towns of Budva and Bar[18] which became the new capital of the remaining part of his despotate.

In the period between 1 July 1440 and his arrival at Bar, the Ottoman forces defeated some military units from Novo Brdo in a battle near Makreš (a village near modern-day Gnjilane).

Stephen Vukčić, who was an Ottoman vassal at that time, used the weak position of the Serbian Despot and tried to capture Zeta.

[28] Branković realized that he lost all of his territory and power base which supplied him with troops necessary to secure his suzerainty, so he moved to his estates in Hungary.

[34] The siege and its aftermath were described in Memoirs of a janissary, written in 1490—1501 by Novo Brdo resident Konstantin Mihailović, who was one of the boys taken.