An Ayutthayan PrincePrince Thianracha (พระเฑียรราชา) was a son of Ramathibodi II. His half-brother, Prince Chairachathirat, was crowned as the king of Ayutthaya in 1534. King Chairacha elevated Tianracha to Uparaja, but did not confer on him the title of King of Sukhothai. Thianracha joined his brother in the campaigns against Lanna, and,in 1546, led the siege of Chiang Mai.
Chairacha died in 1546. Chairacha's son (and Tianracha's nephew) Phra Kaewfa succeeded to the throne as King Yodfa, with his mother Sri Sudachan as regent. She had Yodfa killed in 1548 and put her paramour on the throne as Khun Worawongsathirat. She made Tianracha her co-regent, but his wife, Sri Suriyothai, advised her husband to become a monk to avoid assassination in turn.
Later that year, nobles led by KhunPirenthorathep and Khun Inthrathep staged a counter-coup, killing Worawongsathirat and Sri Sudachan. Pirenthorathep elevated Prince Tianracha to the throne as Phra Maha Chakkraphat.
 King of AyutthayaMaha Chakkrapat, having been put on the throne by Pirenthorathep, elevated him to the position of king of Phitsanulok as Maha Thammarachathirat, and gave him the hand his daughter, Sawatdirat, in marriage. (Maha Chakkrapat passed over tradition by elevating Pirenthorathep instead of one of his sons; but he, when still Prince Tianracha, had himself never been titular ruler of Phitsanulok.) Khun Inthrathep was rewarded with the regency of Nakhon Si Thammarat.
 Wars with Burma (1548)Upon Maha Chakkrapat's ascension, Tabinshweti marched to Ayutthaya taking the opportunity of the upheavals in Ayutthayan politics to capture the Siamese kingdom.
The Burmese armies stopped near Ayutthaya. Tabinshweti came with the Uparaja (future Bayinnaung), Viceroy of Prome, Governor of Bassein. Maha Chakkrapat also took his whole family (including Sri Suriyothai, Prince Ramesuan the Uparaja, and Prince Mahinthrathirat) to fought the Burmese. At Pukaothong field, Maha Chakkrapat fought the elephant battle (Yuttahadhi) against the Lord of Pyay but was overcame. Sri Suriyothai then rushed to rescue her husband but was slashed to death.
The Siamese then put Narai Sangharn - a culverin on a barge and sailed along the Chao Phraya to fire the Burmese armies. The mission worked. The Burmese armies went on the retreat. However, they ambushed Siamese troops (led by Prince Ramesuan and Maha Thammarachathirat) at Kampaengpetch. The Burmese held the two in captivity and requested for the white elephant as an ransom. Maha Chakkrapat then gave off the elephants in exchange for his son and Maha Thammarachathirat.
 War with Burma (1563)After the war of 1548, Maha Chakkrapat insisted on battling Burmese armies near Ayutthaya, so he heavily fortified the city. He, however, de-fortified other cities in order to prevent the Burmese from taking them as bases. The census was taken to derive all available manpower to war. The arms and horses and elephants (white elephants) was caught and accumulated in the full-scale preparation for war.
Bayinnaug (now king), upon hearing about the white elephants, requested for some. As Maha Chakkrapat refused to gave off his elephant this time, Bayinnaung marched to Ayutthaya. Bayinnaung had captured the whole kingdom of Lanna in 1558. With auxiliary troops from Lanna, Bayinnaung marched a mass army into Sukhothai kingdom. Maha Thammarachathirat then realised the greatness of Bayinnuang army and readily surrendered, giving up Phitsanulok to Bayinnuang and became Burmese tributary. At Chainat, Bayinnaung clashed with Prince Ramesuan's army but was able to break through.
Bayinnaung reached Ayutthaya and laid siege on the city - bombarding the city so immensely that Maha Chakkrapat sued for peace in 1564. Maha Chakkrapat gave white elephants and his son Prince Ramesuan as a captive to Bayinnaung.
The Burmese War of 1563 was also called the War of White Elephant. In 1568, Maha Chakkrapat went into monkhood again and abdicated for his son, Prince Mahinthrathirat.