Conventional views of the 1760-1767 Burmese attacks on Ayutthaya contend that the Burmese were taking advantage of an opportunity to attack a politically and economically weak kingdom. This article adduces evidence from the Burmese chronicles, from accounts by contemporary foreign observers, and from economic history to argue that Burma?s campaigns against Ayutthaya were part of an epic struggle between the two polities that began in the 1500s and continued until the Anglo-Burmese War of 1824-1826. Control of trade was one of the central factors motivating this centuries-long conflict. It was the very strength and wealth of the Siamese kingdom, not its alleged weakness, that motivated the Burmese invaders, who hoped to strike a blow that would knock Ayutthaya out of contention as the trading hub of mainland Southeast Asia.