The Toungoo–Ava War (1538–1545) () was a military conflict that took place in present-day Lower and Central Burma (Myanmar) between the Toungoo Dynasty, and the Ava-led Confederation of Shan States, Hanthawaddy Pegu, and Arakan (Mrauk-U). Toungoo's decisive victory gave the upstart kingdom control of all of central Burma, and cemented its emergence as the largest polity in Burma since the fall of Pagan Empire in 1287.Aung-Thwin and Aung-Thwin 2012: 130–132Lieberman 2003: 151
The war began in 1538 when Ava, through its vassal Prome, threw its support behind Pegu in the four-year-old war between Toungoo and Pegu. After its troops broke the siege of Prome in 1539, Ava got its Confederation allies agreed to prepare for war, and formed an alliance with Arakan. But the loose alliance crucially failed to open a second front during the seven dry-season months of 1540–41 when Toungoo was struggling to conquer Martaban (Mottama).
The allies were initially unprepared when Toungoo forces renewed the war against Prome in November 1541. Due to poor coordination, the armies of the Ava-led Confederation and Arakan were driven back by better organized Toungoo forces in April 1542, after which the Arakanese navy, which had already taken two key Irrawaddy delta ports, retreated. Prome surrendered a month later.Hmannan Vol. 2 2003: 204–213 The war then entered an 18-month hiatus during which Arakan left the alliance, and Ava underwent a contentious leadership change. In December 1543, the largest army and naval forces of Ava and the Confederation came down to retake Prome. But Toungoo forces, which had now enlisted foreign mercenaries and firearms, not only drove back the numerically superior invasion force but also took over all of Central Burma up to Pagan (Bagan) by April 1544.Hmannan Vol. 2 2003: 216–222 In the following dry season, a small Ava army raided down to Salin but was destroyed by larger Toungoo forces.
The successive defeats brought the long simmering disagreements between Ava and Mohnyin of the Confederation to the forefront. Faced with a serious Mohnyin-backed rebellion, Ava in 1545 sought and agreed to a peace treaty with Toungoo in which Ava formally ceded all of Central Burma between Pagan and Prome. Ava would be beset by the rebellion for the next six years while an emboldened Toungoo would turn its attention to conquering Arakan in 1545–47, and Siam in 1547–49.
Background
Early 16th century Upper Burma
In the early 16th century, the present-day Myanmar (Burma) comprised several small kingdoms. The Ava Kingdom, the principal power in Upper Burma in the 14th and 15th centuries, had been fighting a long losing war against an alliance of its former vassal states: the Confederation of Shan States and Prome (Pyay). Another former vassal state Toungoo (Taungoo), hemmed in by the Bago Yoma range in the west and the Shan Hills in the east, stayed out of the internecine warfare raging in Upper Burma. As the only peaceful state in Upper Burma, Toungoo had received a steady stream of refugees.Aung-Thwin and Aung-Thwin 2012: 115–116
Then, in 1527, the Confederation finally defeated Ava,Hmannan Vol. 2 2003: 136 and in 1532, its erstwhile ally Prome.Hmannan Vol. 2 2003: 140 Its paramount leader Sawlon I of Mohnyin had now reunited most of Upper Burma and cis-Salween Shan states for the first time since 1480. Toungoo, the only remaining holdout, was his "obvious next target."Fernquest 2005: 356 Fortunately for Toungoo, Sawlon I was assassinated in 1533 on his return trip from Prome, and his son and successor Thohanbwa, based out of Ava, was not accepted as the first among equals by other saophas (chiefs) of the Confederation.Harvey 1925: 107 Without a strong leader, the Confederation suddenly ceased to be a unified force capable of combined action.Harvey 1925: 153
Toungoo's gambit
The Toungoo leadership nonetheless concluded that their kingdom "had to act quickly if it wished to avoid being swallowed up" by the Confederation. In 1534, Toungoo began raiding Pegu's territory to the south in a gambit to break out of its increasingly narrow realm. Although a united polity of Toungoo and Pegu could in theory challenge their possessions in western central Burma (the Prome to Pagan corridor along the Irrawaddy), the Confederation's fractured leadership took no action. They apparently did not believe that the tiny Toungoo could defeat the larger, wealthier Pegu; or that Pegu's weak leader Takayutpi, who was also facing an internal rebellion by Martaban (Mottama), could conquer either Toungoo or Martaban, much less pose a threat to Prome.
At first, their nonchalance proved justified: Toungoo's annual dry-season raids of Lower Burma (1534–37) all failed while Pegu could not organize a counterattack against either Toungoo or Martaban.Hmannan Vol. 2 2003: 185–187 Closer to the battleground, however, King Narapati of Prome was increasingly concerned by Toungoo's deeper and longer raids with each successive campaign, and raised the alarm with Ava. In 1538, Prome, presumably with Ava's permission, entered into an alliance with Takayutpi.Hmannan Vol. 2 2003: 189 Though he had now taken sides, Thohanbwa still did not see a compelling reason to commit his troops, or ask his Confederation allies for additional troops. Indeed, no Ava or Confederation troops were in Prome at the start of the 1538–39 dry season when Toungoo would change the course of history.
First Toungoo siege of Prome (1538–39)
In late 1538, Toungoo again opened its annual dry season campaign. It would have been like any previous one except that in a series of improbable events, Toungoo went on to conquer Lower Burma (except Martaban) in a blitz. By using a stratagem, Toungoo armies took Pegu without firing a shot.Harvey 1925: 154 A few weeks later, Hanthawaddy's larger but poorly led forces were decisively defeated at the Battle of Naungyo by light forces of Gen. Kyawhtin Nawrahta (Bayinnaung). Only a weakened Hanthawaddy force made it to Prome.Harvey 1925: 154–155
The rapid turn of events caught everyone by surprise. Narapati immediately asked Ava for help.Hmannan Vol. 2 2003: 141, 192 While a flatfooted Thohanbwa scrambled to round up the troops, about 7000 Toungoo land and naval forcesAt the start of the chase of Takayutpi, the combined strength of Toungoo's army and navy was 8000 (4500 army, 3500 navy) per (Hmannan Vol. 2 2003: 190–191). But they must have lost a portion of the 1000-strong regiment at the battle of Nyaungyo. converged on Prome, the gateway to central Burma. But the city's fortified defenses held out long enough. Finally, 5000 Ava troops arrived in 300 war boats to break up the siege, and chased Toungoo forces back to the delta. The Confederation's advance was halted at Inbyaw Island () where six Confederation commanders, including Gen. Nawrahta of Kanni, were captured in a naval battle.Hmannan Vol. 2 2003: 194
It turned out to be the last battle of the season. Despite Takayutpi's repeated urges to push on, his allies decided not to proceed any further.Sein Lwin Lay 2006: 170 A deeply frustrated Takayutpi died soon after while trying to catch wild elephants for his army. Narapati too died shortly after from dysentery.Sein Lwin Lay 2006: 172–173
First interlude (1539–41)
An uneasy stalemate ensued. In order to consolidate his gains in Lower Burma, Tabinshwehti moved his capital to Pegu in 1539; reappointed former Hanthawaddy lords to their posts; and appointed many of them to the highest positions of his government. By successfully gaining the loyalty of Hanthawaddy officials, the king now controlled much of Lower Burma's manpower and trade wealth, and for the first time gained access to Portuguese mercenaries and their firearms. This fortuitous combination of Toungoo's "more martial culture", and Lower Burma's manpower, access to foreign firearms, and maritime wealth to pay for them would enable the men from a "small frontier outpost" to further wage war on their neighbors in the following decades.Lieberman 2003: 151, 274
Other polities in the region were now forced to act. The chiefs of the dormant Confederation finally agreed to prepare for war. The western kingdom of Arakan (Mrauk-U) agreed to an alliance with Ava to defend Prome.Hmannan Vol. 2 2003: 195 At Martaban, the only remaining independent Hanthawaddy province, its ruler Saw Binnya had completely fortified his wealthy port, and enlisted Portuguese mercenaries and warships in his service.Harvey 1925: 155–156
The Toungoo command decided to pick off Martaban first. In November 1540, three Toungoo armies (13,000 troops, 2,100 horses, 130 elephants), laid siege to Martaban.Maha Yazawin Vol. 2 2006: 149 Seven months later, Toungoo forces brutally sacked the city, completing Toungoo's conquest of all three Hanthawaddy provinces.Htin Aung 1967: 106 Although the siege presented the Confederation and Arakan with several opportunities to attack Toungoo's lightly defended northern perimeter and southern delta,Chronicles (Maha Yazawin Vol. 2 2006: 148–149) mention only Pegu and Toungoo with rearguard forces. they took no action. Even after Martaban's fall, they still did not raise armies to reinforce Prome. They appeared to have calculated that Tabinshwehti would take a break in the upcoming dry season (as he took a break in 1539–40 after his 1538–39 campaign). By the start of the next dry season in November 1541, neither Ava nor Mrauk-U had raised any sizable standing armies that could be dispatched to Prome.
Second Toungoo siege of Prome (1541–42)
The allies' indecision and lack of preparation would come back to haunt them. It turned out that Tabinshwehti had decided to attack Prome right after the rainy season when no one expected him to. He secretly prepared for war throughout the rainy season (June to October) of 1541. Only King Minkhaung of Prome reinforced his city's defensive fortifications, and stockpiled supplies and provisions.Sein Lwin Lay 2006: 192
Siege of Prome By November, Tabinshwehti had assembled a 17,000-strong naval and land invasion force, his largest mobilization to date. His 13 naval squadrons (9000 troops, nearly 1400 war boats and transport boats) were commanded by ethnic Mon lords of Lower Burma while his army (8000 troops, 2500 horses, 300 elephants) were led by himself and Bayinnaung. As in Martaban, his troops now included much prized Portuguese mercenaries and their firearms. Their plan was to take Prome quickly before Ava and Mrauk-U had time to come to its aid. In case of a long siege, they would take positions around the city that would prevent Ava and Arakan forces from linking up, and they would drive the enemy separately.Sein Lwin Lay 2006: 189, 193–194 They however did not plan for a large Arakanese seaborne invasion; the delta was largely undefended. They believed their war boats intended for Prome, if necessary, could sail down to meet the Arakanese navy in the delta.Hmannan Vol. 2 2003: 208 Only the capital Pegu was defended with a rearguard army.Hmannan Vol. 2 2003: 204
Right after the Buddhist Lent, on 19 November 1541,(Sein Lwin Lay 2006: 186): 1st waxing of Tazaungmon 903 ME = 19 November 1541 Toungoo naval and land forces invaded. As expected, Confederation and Arakanese forces had not arrived.Hmannan Vol. 2 2003: 206 Taken by surprise, Prome's allies frantically raised their armies and navies. Their armies were to break the siege while the well-regarded Arakanese navy, equipped with Portuguese weaponry and mercenaries, was to invade the delta from the south.Hmannan Vol. 2 2003: 205, 207
Meanwhile, Toungoo forces launched attacks to take the city but could not break through the fortified city's musket and artillery fire. They were forced to set up a perimeter around the city.Hmannan Vol. 2 2003: 206
Battle of northern Prome