marching to Ava, as ordered. When Nanda retook Ava, Naresuan withdrew and at Martaban, declared independence. A hastily planned expedition followed Naresuan in the midst of the rainy season. The 12,000-strong Burmese army was caught unprepared by the flooded countryside by the Chao Phaya, and was nearly wiped out by Siamese on their war canoes. Another expedition was launched from Lan Na in March 1586. Mingyi Swa's 12,000-strong army could not take a heavily fortified Lampang, and had to withdraw in June. On 19 October 1586, Nanda himself led an army of 25,000, and invaded again. After several futile attacks on the heavily fortified Ayutthaya, the Burmese retreated in April 1587 after having suffered heavy casualties. The failures at Siam began to affect Pegu's ability to hold on to other regions. Pegu faced other rebellions in Shan states, at Inya (1587–1588) and at Mogaung (1590–1592). In December 1590, Mingyi Swa's 20,000-strong army invaded again. Like in 1586, he could not get past the Siamese fort at Lampang, and was driven back in March 1591. In December 1592, another invasion force of 24,000 tried again. The armies penetrated to Suphan Buri near Ayutthaya where they were met by Siamese forces led by Naresuan. On 8 February 1593, the two sides fought a battle in which Mingyi Swa was slain. The Burmese chronicles say Swa was killed by a Siamese mortar round while the Siamese sources he was killed by Naresuan in a duel on their war elephants. The Burmese forces retreated. It was the last of Pegu's Siamese campaigns. The main reason for Nanda's failure was that unlike his father who raised armies of 60,000 and 70,000, Nanda could never muster a force larger than 25,000 at any one time. Worse yet, he had frittered away Pegu's manpower. About 50,000 of the total of 93,000 men that marched in the five Siamese campaigns had perished. Unraveling of the empire Pegu was now a completely spent force, vulnerable to internal rebellions and external invasions. In December 1594, Siamese armies invaded, and laid siege to Pegu in January 1595. Burmese armies from Toungoo and Chiang Mai relieved the siege in April 1595. However, the entire Tenasserim coast to Martaban now belonged to Siam. During the Siamese siege of Pegu, the viceroy of Prome, Mingyi Hnaung, revolted against his father. Nanda was powerless to take any action. Others soon followed. In early 1597, vassal