Prince Natshinnaung, cousin of Anaukpetlun, the sixth king of the Toungoo Dynasty of Burma, is deeply dissatisfied with his reduced status as viceroy of Toungoo and secretly forms an alliance with Portuguese mercenary Filipe de Brito e Nicote, who had been made governor of Thanlyin (Syriam) in 1599 after leading Rakhine force sin the capture of the port city.

Brito had declared independence from his nominal Rakhine masters in 1603, defeated the invading Rakhine navy in 1604 and 1605, and successfully established Portuguese rule under the Portuguese viceroy of Goa.

Natshinnaung invites de Brito to attack Toungoo.

When de Brito's attack fails, Natshinnaung accompanies de Brito, who he calls his "blood brother", back to Thanlyin.

Converting to Roman Catholicism, he is baptized by a priest from Goa.

Burmese forces of King Anaukpetlun now besiege De Brito's Thanlyin.

Anaukpetlun offers to pardon his cousin if Natshinnaung will take an oath of allegiance.

Natshinnaung refuses, saying that he has already taken baptism, and that he is ready to die with de Brito.

During the last days of the siege, The king reportedly says, "You prefer to be the slave of a foreigner than serve the king of your own race", and orders his execution after the fall of the city in September 1613.

De Brito is executed by impalement, a punishment reserved for defilers of Buddhist temples.