The Ottoman threat was building to the east, threatening Bosnia and its southeastern regions in Hum. On 27 August 1388, Grand Duke Vlatko defeated an Ottoman raiding party (probably up to 18,000 strong) in the Battle of Bileća. Bosnian heavy cavalry is typically credited with winning the battle as they broke the Ottoman ranks and pursued the retreating enemy. Celebrated Ottoman commander Lala Sahin Pasha (, 1330 – cca 1382) barely managed to save himself with the small band of his soldiers.