Against Musa was created a broad coalition, in which the Ottoman commanders from some parts of the Balkans, and his only remaining brother, Mehmed I, who ruled part of former Bayezid Asian countries, joined them. His first attempt to cross into Europe 1411 was finished with defeat, but they kept fighting on other fronts, so that by the end of that year Stefan, and Skopje and Kyustendil Beylerbey's attacked the country of Musa. Winter weather and swollen river Marica have prevented the connection of their and Mehmed I's forces over the Ser area. The answer to this attack came in the early 1412 when Musa from around Serdica and Čemernik fell over in Vranje area and looted it, while Uglješa Vlatković, who ruled that part of Serbian Despotate, barely saved himself. His forces then continued with march to Novo Brdo, but the news of the arrival of Despot Stefan-led, he left Serbia and went to Thessaloniki and Thessaly.