Thai War of 1442 - 1448 (King Sri Sutham Tilok)
King Sam Fang Ken who died in 1442 was forced to abdicate by his sixth son, Prince Chao Lok born in 1411 -87 who assumed the throne as King Sri Sutham Tilok. Immediately a dynastic dispute arose when Sam Feng Kens tenth son, Prince Chao Joi refused to support his brother king, brought his father into town of Muang Fang, and began a war to take power. When Sri Sutham Tilok seized Muang Fang, Chao Joi abandoned his father and fled to Thoen, where he successfully urged the towns governor to seek help from King Boromoraja II, who seeking to extend his influence, was glad to march with troops to aid Chao Joi.
However, before the arrival of Boromoraja at Thoen, the forces of Sri Sutham Tilok attacked, Chao Joi and the governor were killed. While on march, Boromoraja took captives until his advance was blocked by Chiengmai forces, which employed Laotian spies to infiltrate the Ayutthayan army and stampeded their war elephants by cutting of their tails. In the midst of the ensuing chaos, Chiengmai soldiers attacked and defeated the Ayutthayan troops. King Boromoraja became ill, returned home, and in 1448, he again led another Chiengmai invasion but died before it was completed.
Thai War of 1451 - 1456 (King Boromo Trailokanat)
Ayutthaya was militarily strengthened under King Boromo Trailokanat, (died in 1488) who desired ascendancy over Chiengmai. In 1451, an insurrection broke out in the former Sukhothai kingdom against Ayutthayan rule; the Sawankhol town leader and others asked King Sri Sutham Tilok for help in an attempt to regain their independence. As a result, Tiloks forces were compelled to withdraw. An Ayutthayan offensive led to the occupation of Chiengmai in 1452. later Luang Prabangs Laotian king, Sai Tia Kaphat who died in 1479, intervened in the war, forcing the Ayutthayans to retreat and the Chiengmais to defend themselves. A Chiengmai army later invaded Ayutthayan territory and briefly held Kamphaeng Phet; hostilities halted temporarily afterward.
Thai war of 1461 - 1464
The kingdoms of Ayutthaya and Chiengmai fell into hostilities after the conspiratorial town ruler of Sawankhalok left and became head of the Chiengmai town of Phayao. In 1461 Chiengmai forces under King Sri Sutham Tilok invaded Ayutthayan lands, moving south to take Sukhothai and besiege Phitsanulok. But a Chinese attack from Yunnan province on Chiengmai forced Tilok to withdraw his troops from Ayutthaya. In 1463 King Boromo Trailkanat transferred his Ayutthayan capital to Phitsanulok in order to gain a more centralized and tighter military control. His forces repulsed another Chiengmai
invasion and assault on Sukhothai, driving the invaders well back into their own lands.At
the battle of Doi Ba, fought in the moonlight and with the use of war elephants, the
Chiengmai troops drove the Ayutthayan forces into a swamp and forced them to retreat.
peace was restored in 1464.
Thai war of 1474 - 1475
In 1474, diplomatic encounters between Ayutthaya and Chiengmai to settle their differences only resulted in more bloodshed, an Ayutthayan invasion brought on the seizure of Chiengmai territory.
In 1475, King Sri Sutham Tilok of Chiengmai whose forces suffered setbacks, sued for peace, though no formal peace was made, hostilities ceased for about ten years until envoys from Ayutthaya were murdered by Tilok.
In 1486, Another Ayutthayan invasion of Chiengmai was inconclusive and the fighting ended with the death of king Sri Sutham Tilok.
Thai War of 1492 (King Rama Thibodi II 1472 -1529)
War erupted once again between Chiengmai and Ayutthaya, this time over a Crystal Statue of Buddha which was stolen from Chiengmai by the son of King Rama Thibodi II of Ayutthaya, when he was in Chiengmai as a Buddhist priest. When Chiengmais King Phra Yot (1487-95) promptly attacked Ayutthaya .and forced King Rama Thibodi II to give back the statue taken by his son
Thai war of 1500 - 1529
In 1507, Chiengmais King Ratana began an offensive into Ayutthayan territory, but his forces were repulsed in a hard fought and bloody battle near Sukhothai. The next year Ayutthaya took the initiative with an invasion of Chiengmai; after taking Phrae, the invaders lost a bloody battle nearby and were forced to withdraw.
In 1510 another Ayutthayan invasion fared no better, and skirmishing persisted for five years until Chiengmai forces attacked Sukhothai and Kamphaeng Phet. King Rama Thibodi II and his two sons mounted a strong offensive, evicting enemy troops and pushing them into Chiengmai as far as the Wang River, Near Lampang; there Rama Thibodi was victorious in battle, then looted Lampang and carried away the Crystal Buddha statue stolen from Chiengmai by Rama Thibodis son earlier in 1492.
The Ayutthayans had received crucial Portuguese support (guns and a training corps) in this campaign. By the time of King Rama Thibodis death in 1529, Chiengmai forces had been ousted from Sukhothai and other Ayutthayan towns.