Burmese–Siamese War (1568–1569)

War of the first fall of Ayutthaya
	; War elephants depicted from a later Siam–Burma war.
Date	1568–1569
Location	Ayutthaya, Phitsanulok, Lan Xang, and Kamphaeng Phet
Result	Burmese victory
Belligerents
Ayutthaya Kingdom (Siam) ; Lan Xang Kingdom	Toungoo dynasty ; Sukhothai Kingdom; Lan Na Kingdom;
Commanders and leaders
Maha Chakkraphat † ; Mahinthrathirat (POW); Setthathirath	Bayinnaung ; Mahathammarachathirat; Thado Minsaw; Binnya Dala
Units involved
Royal Siamese Army; Royal Siamese Navy; Lan Xang Army ; Luzon Mercenaries	Royal Burmese Army; Royal Sukhothai Army; Royal Lanna Army; Portuguese mercenaries
Strength
Unknown	Burmese sources: Bayinnaung's five armies Invasion force:; 54,600 men, 5,300 horses, and 530 elephants; Combined with Phitsanulok army:; 70,000+
Casualties and losses
Siam ; Unknown ; Lan Xang ; 30,000 troops and 100 elephants	Unknown

The Burmese–Siamese War (1568–1569) also known as the War of the first fall (สงครามคราวเสียกรุงครั้งที่หนึ่ง) was a military conflict fought between the Kingdom of Ayutthaya (Siam) and the Kingdom of Burma. The war began in 1568 when Ayutthaya unsuccessfully attacked Phitsanulok, a Burmese vassal state. The event was followed by a Burmese intervention which resulted in the 2 August 1569 defeat of Ayutthaya, which became a Burmese vassal state. Burma then moved towards Lan Xang, occupying the country for a short period of time until retreating in 1570.