After losing their capital, the Laotians rallied. There are, however, multiple versions of this part of the war. One account reported that Then Kham, a son of the Laotian king, who was serving as the governor of Muong Dan Sai, attacked the Vietnamese with fresh units of the Lao army. In this history, the exhausted and depleted Vietnamese were defeated at the Battle of Pāk Phūn and then straggled back to Đại Việt. The Vietnamese forces pushed the Laotian resistance all the way to the upper Irrawaddy River, eventually reached the Burmese kingdom of Ava. Lê Thánh Tông while camping in today Laotian-Burmese border, sent a welcome letter to the king of Ava in Central Myanmar.