Dàgū

Dagu guards the mouth of the Hai River, where ships approaching Tianjin enter from the Bohai Sea. The estuary was a gateway to the waterways leading toward Beijing, and its defence concerned successive governments. A temple to the sea god stood here from the Ming period and was repaired during the Kangxi emperor's reign. In the early nineteenth century the Qing strengthened the entrance with naval forces and batteries on the riverbanks.