Toungoo–Mrauk-U War

By mid-1546, the war in Upper Burma had reached a stalemate with the rump Ava Kingdom further splitting into two halves: the Mohnyin-controlled west of the Irrawaddy (present-day Sagaing Region and southern Kachin State), and Onbaung–Hsipaw-controlled eastern half (approximately, northern Mandalay Region and western Shan State).[23] The Toungoo command cautiously decided that it was safe to launch a major campaign in Arakan in the following dry season. By October 1546, they had raised a sizable invasion force (19,000 men, 400 horses, 60 elephants) as well as a number of rearguard forces. Because of the challenging terrain of the Arakan Mountains, only 4000 men would invade by land from the Irrawaddy delta. Instead, over three quarters of the invasion forces (15,000 men) would be transported by sea using 800 war boats, 500 armored war boats, and 100 cargo boats.[2] Toungoo now possessed a serious navy, mostly made up of ethnic Mon troops and commanded by former Hanthawaddy lords.[24] The land army was commanded by Nanda Thingyan and Baya Nandathu.[2] Meanwhile, a number of rearguard forces were deployed across the kingdom: the capital Hanthawaddy was defended by regiments commanded by Baya Gamani and Binnya Ein; the southern province of Martaban (present-day Mon State) by Saw Binnya U of Mawlamyine; Toungoo in east-central Burma by Mingyi Swe; Pyay in west-central Burma by Thado Dhamma Yaza I of Prome; and key towns along the northern border, Bagan, Salay, and Taungdwingyi by their local governors.[2]

On the opposing side, the Arakanese kingdom's defenses were well prepared.[24] The capital city of Mrauk U was protected by an extensive network of defensive structures. It was ringed by eleven forts,[note 7] each of which was reinforced with walls, moats, trenches, and lakes. Canals were also set up to interconnect the ring forts. The capital itself was surrounded by a trench, three tiers of moats, and a stone wall with an extensive network of bastions atop the wall. Diversionary canals and lakes ensured the city's water supply in case of a long siege.[25] These were the result of the multi-year defensive construction works project Min Bin launched right after his conquest of Bengal in 1533. The defense works were initially begun to protect the capital region from rampant seaborne raids by Portuguese pirates, and later expanded to defend against Toungoo invasions.[note 8] At the start of the campaign, the capital region was defended by no less than 20,000 troops. A 35-ship Arakanese fleet, largely manned by Portuguese mercenaries and commanded by Min Dikkha, sailed down to Cape Negrais to block a possible seaborne invasion.[4]

1546–47 campaign

On 28 October 1546, Toungoo naval and land forces began the campaign.[note 9] The Toungoo high command, including Tabinshwehti, traveled by sea.[note 10] The Mrauk U navy, waiting around Cape Negrais, initially thought about engaging Toungoo vanguard squadrons but decided against it when they saw the size of the invasion fleet.[26] The fleet sailed up the Arakan coast unopposed, and dropped off troops south of Thandwe. They joined up with the army that had just crossed over the Arakan Mountains. Bayinnaung now assumed command of the combined armies.[26] Then Toungoo land and naval forces converged on Thandwe. The Mrauk U navy defended the port but was defeated by sheer numbers.[3] Mrauk U land forces evacuated Thandwe.[2] Tabinshwehti appointed Min Aung Hla as the viceroy of Thandwe, and left Nanda Kyawhtin, Governor of Thanlyin, in charge of the city's defenses.[27]

By January 1547, Toungoo land and naval forces had left Thandwe for Mrauk U. The Arakanese defenses now awaited from their capital defense zone. A 5000-strong elite army, equipped with foreign firearms, defended the capital while another 15,000 troops were posted at forts around the capital.[4] By the second half of January, Toungoo forces converged onto the capital region. Invasion armies approached from the southeast while another army and war boats entered the Kaladan River from the southwest. Arakanese defenses successfully drove back the seaborne invasion force near Po-Chi Island.[3] But they could not stop the Toungoo army at Launggyet, which fell on 23 January 1547.[28] Tabinshwehti did not pause. Toungoo troops began their final push the very next day. They overcame Arakanese defenses, and breached the eastern outworks of Mrauk U. But Min Bin opened the sluices of the city's reservoirs, flooding out many Toungoo troops and creating an impassable moat.[22] Toungoo forces were now reduced to shelling from afar. But their Portuguese supplied cannon had little effect against Mrauk U's stone walls.[27]

The Toungoo forces were again in for a long siege. Although the Toungoo forces had successfully sacked other fortified cities after long sieges (Martaban in 1540–41, Prome in 1541–42), the Toungoo high command realized overcoming Mrauk U's elaborate defenses in four months before the rainy season would be difficult. Further complicating matters, Tabinshwehti received news that Siamese forces had occupied Dawei, which Toungoo had claimed.[24][29] The Upper Tenasserim peninsula was defended by the garrison at Moulmein but the Toungoo command was nonetheless concerned. They advised against a long siege, warning that it would be extremely difficult to get back to Lower Burma during the monsoon season since the troops could not use the sea, and would have to pass the Arakan Yoma range, a difficult proposition even in the dry season. Given that the home country was still vulnerable to possible external attacks, they advised the king to accept a compromise with Min Bin.[30] Likewise, Min Bin may have wanted a quick truce since he had heard that Tripuri marauders were raiding his northern possessions in Bengal down to Ramu.[31]

Burmese and Arakanese chronicles disagree as to which side began the offer for negotiations. The Burmese chronicles say that a few days after the siege, the Mrauk U court sent four monks with a peace proposal.[32] The Arakanese chronicles however say that Toungoo proposed first, stating that Min Bin at first refused to see Tabinshwehti's emissary Bayinnaung, and agreed to see him only on the second day.[33] The negotiations went on for a few days. The Burmese chronicles say that Min Bin agreed to restore Min Aung Hla as the viceroy of Thandwe and seven southern townships in exchange for peace, and that the two kings exchanged gifts, including two war ships by Tabinshwehti.[34] But the Arakanese chronicles say only that Tabinshwehti presented lavish gifts to Min Bin before retreating.[6] At any rate, the two sides reached agreement on 30 January 1547, allowing an orderly withdrawal of Toungoo forces.[note 11] Toungoo forces withdrew from Mrauk U beginning on 2 February 1547, but two regiments remained stationed at Thandwe for three more months per agreement.[35]