At the turn of the nineteenth century, the Qing state confronted its most serious maritime threat since the conquest of Taiwan in 1683. From the 1790s to 1802, huge Chinese pirate fleets allied with the newly unified Vietnamese state (Tayson regime, 1778-1802) and ravaged the coastal frontier of South China. Worse yet, Britain, hoping to grab a much-needed foothold in East Asia, launched two naval expeditions to occupy Macao, a long-time Portuguese settlement under Chinese ownership, in 1802 and 1808. This paper takes the Sino-Vietnamese pirates and British intruders as a prism to view the complexity of the Qing’s oceanic governance. Furthermore, it examines how this dramatic combination of transnational and global crises affected the Qing’s notions of maritime sovereignty and suzerainty before the full onslaught of Western aggression in the first Opium War. As the first step, this paper studies the contested constructions of oceanic space in late imperial China and how those constructions shaped government policies and precipitated violence at sea. It also throws new light on the contingent, piecemeal and experimental nature of British imperialism in China.