This chapter attempts to reconstruct high Qing coastal defense. It uncovers the historical background and overall structure of maritime militarization in the high Qing, including the establishment and construction of naval bases, warships, and coastal fortresses that have largely been overlooked, especially by Western historians. In fact, almost nothing has been written extensively about eighteenth-century Qing naval development in the anglophone historiography. This chapter reviews the measures used to strengthen and maintain the military defenses of the seven coastal provinces that were bounded by four interconnected strategic sea zones, namely the Guangdong sea zone, the Taiwan Strait, the Jiangsu–Zhejiang sea zone, and the Bohai area. It provides a picture of the strategic complexities that high Qing emperors faced along the empire’s extensive coastlines and the policies they adopted to address them.