Murad II
On 6 August 1439 the Ottoman forces under Ishak-Beg defeated Serbian forces near Novo Brdo. The Ottomans captured Smederevo on 18 August 1439, reducing the territory of the Serbian Despotate to Zeta and a region around Novo Brdo. The forces under Murad II joined Ishak-Beg to attack Novo Brdo, but its garrison successfully repelled their attacks. 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. Before they did so, they robbed caravans of Ragusan merchants, while Murad II went to Adrianople.