Why did Qianlong’s military expeditions weaken Qing finances?

During the reign of the Qianlong emperor, the Qing dynasty reached its greatest territorial extent through a series of extensive military campaigns, including expeditions in Xinjiang, Tibet, Myanmar, Vietnam, and Taiwan.12

The primary reason these military efforts weakened the state was the enormous financial cost associated with maintaining such a long and geographically diverse series of expeditions. While the Qing state had maintained healthy surpluses throughout much of the 18th century, the cumulative expense of these campaigns eventually depleted the imperial treasury.13

This fiscal strain was further exacerbated during the final two decades of Qianlong’s reign by widespread corruption and mismanagement, particularly under the influence of his favorite official, Heshen. By the year 1800, the state's remaining surpluses were ultimately exhausted by the long campaign required to suppress the White Lotus Rebellion, leaving the government in a state of fiscal weakness that persisted into the 19th century.134