In 1592, Nanda Bayin ordered his son Minchit Sra to attack Ayutthaya. The Siamese army, under King Naresuan, met the Burmese army at Nong Sarai on Monday 18 january, 1593.

The personal battle between Naresuan and Minchit Sra is now a highly-romanticised historical scene known as Yuddhahatthi, the Elephant battle. After narrowly missing Naresuan and cutting his head, Minchit Sra was slashed to death on the back of his elephant. This was on Monday, the 2nd waning day of the 2nd month of the Buddhist calendar Chulasakarat Era year 954. Calculated to correspond to Monday, 18 January, AD 1593 of the Gregorian calendar, this date is now observed as Royal Thai Armed Forces day.