At Pagan , Narathihapate deliberated with his court for an appropriate response but ultimately refused to submit . The Burmese court may have been counting on another limited border war but the emperor now ordered an invasion of northern Burma . ( He also ordered an invasion of Champa , whose king too had refused to submit . ) The Burmese king 's troubles did not go unnoticed elsewhere in the kingdom . In the same year , a usurper named Wareru seized the southern port city of Martaban ( Mottama ) by killing its Pagan @-@ appointed governor . Although the king 's three sons were viceroys of the nearby Lower Burma cities ( in Bassein ( Pathein ) , Prome ( Pyay ) , and Dala ) , the king , preoccupied with much more serious threat in the north , did not ( or could not ) take no action on Martaban .