[3] Despite the initial gesture, he did not respect the 15-year-old king, who proved to be utterly disinterested in governing and spent his time in "frivolous amusements with bad companions".
His deputy Binnya U, governor of Moulmein (Mawlamyaing), was also married to a sister of Takayutpi but nonetheless was more loyal to him than the high king.
Using the trade wealth, he was able to assemble a formidable military which by 1540 employed expensive Portuguese mercenaries, their firearms and warships.
[6] He essentially declared independence from Pegu in 1534 by refusing to contribute to Takayutpi's war effort against Toungoo Dynasty as vassals were obligated to do.
When Toungoo finally took Pegu in late 1538, Takayutpi so distrusted Saw Binnya that he chose to retreat to Prome Kingdom, another state, rather than to Martaban.
In fact, the Toungoo command after the conquest of Pegu deliberated an attack on Martaban that would have begun in November 1539 but decided against it, citing the city's strong defenses.
Saw Binnya finally offered to surrender provided that he be allowed to remain viceroy in exchange for an annual tribute of 30,000 viss (48,987.9 kg) of silver bullion and other valuable presents.
A Portuguese captain listed the treasure as consisting of two shiploads of gold and silver, and 26 chests of precious stones.
[10] At the same time, Saw Binnya offered a large bribe to João Caeiro, the leader of Portuguese mercenaries fighting for Toungoo, to help him and his family escape.
[11] In May 1541, after a seven-month siege, Toungoo naval forces led by Adm. Smim Payu broke through the seven Portuguese ships at the harbor, and the city's defenses were breached.
Inside the city, Saw Binnya, described as athletic and brave, led his forces atop a war elephant against the invaders.
The mass execution had the desired effect: The remaining vassals of Martaban down to the Siamese border duly submitted to Toungoo.