The Ottomans installed a strong garrison and brought Muslim settlers from Asia Minor. On the following year fell Serres The new Ottoman success did not bring together Ivan Shishman and Ivan Sratsimir. Between 1384 and 1386 a war broke out between Bulgaria and Wallachia, and the Vlachs seized several settlements along the Danube but were later defeated and their "voivoda" Dan I was killed. Ivan Sratsimir took part in the action as an ally of the Vlachs which deepened the mistrust between the two brothers.