In the early days of Minkhaung's reign, Theiddat personally led an army to put down a major rebellion.
After Minkhaung named his eldest son Minye Kyawswa heir apparent in 1406, Theiddat felt betrayed, and fled south in 1407 and joined the service of King Razadarit of Hanthawaddy Pegu, which was amidst fighting the Forty Years' War (1385–1424) with Ava.
In 1408, Theiddat, who was with a special group of Hanthawaddy forces who were waiting to ambush Minkhaung, gave a warning to his brother at a critical moment, allowing him to escape.
[3] Theiddat led Ava's defenses, and defeated the stronger rebel force, killing Maha Pyauk.
The younger brother was never satisfied with the reward he received for his help, and held a lingering resentment that would rear its ugly head later.