Seeing the Ming Empire distracted by the rebellion in its Mornaean colony, Britain seized the opportunity to expand its influence in Southeast Asia, formally declaring war in 1784. The Royal Navy blockaded Ming territories in the South China Sea while the English Indies Company (EIC) launched an invasion of Siam using a force composed largely of Bengali and Burmese troops. Initially, the British achieved tactical success, defeating Siamese forces at the Battle of Pai in 1785. However, the Ming court decided to prioritize the threat on their own borders over the distant colonial uprising, deploying Imperial regulars to bolster their Southeast Asian tributaries and halting the British advance.

The British offensive unraveled completely in 1786 during the disastrous Battle of Sik in Malaya. Suffering from disease, poor logistics, and false intelligence regarding reinforcements, EIC commander Henry Ratcliffe launched a desperate attack against a numerically superior Ming-Siamese army. The well-equipped Ming forces utilized their artillery advantage to decimate the EIC troops, inflicting massive casualties and forcing the British into a chaotic retreat that effectively destroyed their military presence in the region.

Simultaneously, the Royal Navy suffered a humiliating defeat at sea during the Battle of Hainan. A British fleet, scattered by a typhoon that damped their gunpowder stores, was intercepted by a Ming naval force. Unable to return fire effectively and trapped by unfavorable winds, the British lost multiple capital ships in a one-sided engagement that shattered the reputation of British naval invincibility in the Pacific.

Faced with these twin military catastrophes and growing political unrest at home, the British government abandoned its ambitions of Asian conquest. King Henrik, turning against the hawkish Whig faction, sought peace to prevent further losses. The conflict concluded with the Treaty of Beijing in 1787, a compromise in which the Ming Empire agreed to recognize the independence of the United Provinces of Mornaea to cut their colonial losses, while Britain was forced to completely withdraw from Siam and Malaya, securing the Ming sphere of influence in Southeast Asia.