The decline of authority of the Qing dynasty had caused the rise of numerous pirate groups, active around the commercially important Pearl River Delta, that captured trade vessels, assaulted seaside populations or forced them to pay tribute, but did not interfere with European shipping initially.

[2] As part of the Napoleonic Wars, the British established a garrison in Macau in September 1808 in order to prevent the colony from falling into French hands, though they did not make any moves against Chinese pirates.

Subsequently, the Loyal Senate of Macau (the Leal Senado) armed three ships, commanded by artillery captain José Pinto Alcoforado de Azevedo e Sousa with categorical orders to conduct a punitive expedition against the pirates.

Finally, on January 21, Cheung Po Tsai mobilized his entire fleet, numbering over 300 ships, 1500 guns and 20,000 men, in a last-ditch attempt to defeat the small Portuguese flotilla, anchored by Lantau Island.

Upon seeing the pagoda-ship disappear, the pirate fleet scattered, and most of it retreated into the shallow Hiang San River, where Portuguese ships couldn't enter due to their larger draught.

Instead, Alcoforado decided to board a small dinghy and personally meet Cheung Po Tsai aboard his flagship, amidst the entire pirate fleet.

Cheung Po Tsai was impressed and deeply flattered at the level of confidence that Alcoforado displayed towards him, and promptly agreed to submit to the Chinese Emperor's authority, even going as far as admitting that he was just attempting to buy time to break the blockade.

[9] Cheung Po Tsai requested the moderation of the prestigious ouvidor Arriaga, who agreed to meet them at the Hiang San river along with several Imperial delegates.

Cheung Po Tsai would in the future make formal visits to the Leal Senado of Macau to meet several of the Portuguese officers present at the fighting, among them Gonçalves Carocha.