One ruler with this name had his army ambushed and defeated by the Bulgarian Vinekh at Rishki Pass. 
One ruler with this name had his army ambushed and defeated by the Bulgarian Vinekh at Rishki Pass.  In addition to that ruler with the sobriquet "the Dung-Named," another ruler with this name saw his enemy cut off his trade routes by building the Rumelihisari and smash the walls of his capital with guns constructed by the Hungarian Orban.  Another ruler with this name defeated Maxentius at Milvian Bridge, after seeing a cross in the sky and the words, "In this sign conquer."  Possessed by rulers with epithets "Dragases" and "the Great", FTP, give this name shared by the last Byzantine emperor and a Roman emperor who converted to Christianity. 
One ruler with this name had his army ambushed and defeated by the Bulgarian Vinekh at Rishki Pass.  
Constantine (accept answers with following epithets like "the Great")