Shan States

The Shan state of Mohnyin, centered in the region of present northeastern Burma (Myanmar), has cast off its status as a Chinese tributary and intensifies its raids into the Burmese kingdom of Ava.

Ava attempts unsuccessfully, in 1507, to appease the Shans, who continue their attacks.

The Burmese kingdom of Toungoo to the south declines to answer Ava’s request of support.

Burmese King Tabinshwehti sends his top general and brother-in-law, Kyaw Htin Nawrata, upon whom he has conferred the name Bayinnaung, north in pursuit of Takayutpi, the Mon king of Pegu (r. 1526-1538) who had fled north to seek refuge at Prome.

Bayinnaung faces a superior force on the other side of a river in the famous Battle of Naung Yo.

After crossing the river on a Pontoon bridge (rafts in another version) Bayinnaung orders the bridge destroyed to spur his troops forward in battle and provide a clear signal that there will be no retreat.

Before the battle begins, Bayinnaung also disregards a message from Tabinshwehti ordering him to wait for the main body of troops to arrive.

Bayinnaung replies that he has already met the enemy and defeated them.

To those who criticize this action, Bayinnaung replies that if they lose, they will all be dead anyway and it will not matter whether they are alive or not.

Tabinshwehti is unable to take Prome because it is well defended with strong walls and supported militarily by Shan Ava.

When Takayupti dies, many of his loyal followers join Tabinshwehti's side.

Tabinshwehti increases his military strength by employing mercenaries of many nationalities, including Portuguese and Muslims.

The number of Portuguese soldiers in his employ is said to number as many as seven hundred.

Tabinshwehti, following a coronation ceremony and religious donations at the Shwedagon Paya, where he is crowned “king of all Burma” in 1541, ...

...the newly installed monarch leads an expedition to the north to subjugate Prome, but the initial assaults against the city walls fail.

Prome requests aid from Shan Ava and Arakan.

Thai forces arrive first, but Bayinnaung meets them in advance before they can arrive at the city and defeats them.

The siege drags on and when the rainy season arrives, Tabinshwehti orders his troops to plant rice and gather labor and provisions from Lower Burma.

Bayinnaung ambushes the overland contingent of forces sent by Arakan, causing caused both the Arakanese land and river forces to return home.

After five months of siege, starvation leads to defections and enable the Burmese to easily overcome the weakened defenses.

(The Portuguese writer Fernão Mendes, purportedly an eyewitness, describes in detail the sack of Prome and the punishments that were supposedly meted out to the inhabitants.)

Tabinshwehti now controls Lower Burma; most of the Mon princes become his vassals.

Shan forces lead a counterattack on Prome in 1544, but Tabinshwehti's forces are able to repel the assault.

Tabinshwehti marches north in 1545, taking Pagan and ...

...Salin, where he leaves a garrison.

Instead of driving northwards and reestablishing a Burmese state at Ava, Tabinshwehti turns his attention to the coastal polities to his west and east, Arakan and Ayutthaya.

Burmese king Bayinnaung, intent on subduing the fractious Shan states of Upper Burma, launches a large-scale assault on the north and in March 1555 captures the Shan-held former Burmese capital of Ava.

Burmese forces under Bayinnaung move through the Shan states, taking Hsipaw and other towns in 1556 while advancing southward toward ...

...the Thai kingdom of Chiang Mai, held by Laotian ruler Setthathirat, who has dispatched agents to foment and support rebellions against Burma by the Shan.

Bayinnaung responds by invading in April 1556 and seizing Chiang Mai, which surrenders without a fight.

Electing not to sack the capital, Bayinnaung installs a puppet ruler.