province, the brothers realized that they could not hold out for long. They appealed to the king of Lan Na to intervene, promising a cut of the tax revenue of Martaban and Moulmein ports. At Chiang Mai, King Kue Na was interested. Chiang Mai had wanted to pull Martaban, a former Sukhothai tributary, into its sphere of influence at least since 1351 while Chiang Mai's rival Ayutthaya had claimed all former Sukhothai tributaries since 1350. When he heard that Chiang Mai might again invade, U repaired ties with Chiang Mai by sending his eldest daughter to Kue Na in a marriage of state. Although Chiang Mai's intervention did not materialize, U did not proceed to retake Martaban or the delta. An uneasy ceasefire persisted for the next five years. The brothers controlled nearly two out of the three provinces of the kingdom: Byattaba held the Martaban province, south of Donwun (modern Mon State and southern Kayin State) while Laukpya held the delta (modern Ayeyarwady Region). The king controlled only the northern third of the Martaban province to Donwun, and the all-important Pegu province (modern southern Bago Region and Yangon Region). Renewed fighting (1369–1371) The brothers then launched a surprise attack on Donwun in 1369. Their attack was opportunistic, and came a few days after the death of Chief Minister Pun-So, U's righthand man. During the mourning period, E Bya Bon and 700 warriors, disguised as mourners, managed to get inside Donwun, and seized U's palace. The king fled to Pegu (Bago), about 120 km northwest of Donwun, across the Bay of Martaban, and relocated his capital there. (Although the move to Pegu was made under duress, the move proved permanent. By then, Pegu was the more natural location to be the capital due to its strategic location—between the other two provinces—and its "agricultural and demographic potential". The traditional home of the dynasty, Martaban, on the other hand, was located on the upper Tenasserim coast, and too close to the Tai kingdoms to the east.) The brothers' advantage was fleeting. They tried but neither Byattaba nor Laukpya could make any headway into Pegu throughout 1370–1371. Meanwhile, U secured his rear by successfully negotiating a peace treaty with King Swa Saw Ke of Ava that demarcated the border between the two kingdoms. Soon after the treaty with Ava, U launched a counterattack, which was partially successful. His forces retook Donwun but could