Bayinnaung then led the Burmese armies in mass to Ayutthaya with supports from Maha Thammarachathirat. The Burmese then laid siege on Ayutthaya. Maha Chakkrapat fell ill and died. Mahinthrathirat assumed the throne again. In spite of several months of efforts, Ayutthaya stood still. Bayinnuang then bribed Phraya Chakri - a Siamese general who had been captured during the War of Second Siege of Ayutthaya in 1564 - to be a spy. Mahinthrathirat embraced the returned general with trust. He appointed Phraya Chakri the commander of Siamese armies. Phraya Chakri then placed the less-trained troops in the front. The Burmese then easily defeated the Siamese and eventually took the city in 1569.
Bayinnuand installed Maha Thammarachathirat as the King of Ayutthaya tributary to Pegu. Mahinthrathirat along with his family and the nobility were captured to Pegu. Mahinthrathirat died in the same year on the way to Pegu. Some sources said he insulted Bayinnuang and was then drowned, thus spelling the end to Suphannabhum dynasty.