When Natshinnaung succeeded as king following the death of his father on 11 August 1609, much of the country had been reunited under the leadership of King Anaukpetlun, one of Natshinnaung's cousins. In 1610, Anaukpetlun attacked Toungoo. The city surrendered on 4 September 1610 (2nd waning of Tawthalin 972 ME). Although the king re-appointed him as viceroy of Toungoo, Natshinnaung was deeply dissatisfied with his reduced status. Natshinnaung secretly made an alliance with Portuguese mercenary Filipe de Brito e Nicote, the ruler of Thanlyin, and invited de Brito to attack Toungoo. When de Brito's attack failed, Natshinnaung accompanied his "blood brother" de Brito back to Thanlyin.