On the first day of the third month of the twenty-fifth year of the Emperor Chongzhen era, Wang Yongji ordered Wu Sangui to launch an attack on Jiefan Fortress.
Jiefan Fortress is situated on the south bank of the Hun River and the north bank of the Suzi River. It sits upon a ridge-shaped mountain. Sarhu lies on the south bank of the Hun River, five li away from Jiefan Fortress, also on a ridge-shaped mountain.
In the present day, that location is the site of the Dahuofang Reservoir, which was first constructed in the 1950s. During the Ming Dynasty, however, there was no reservoir there—only a riverine plain. Apart from the river channel itself, the rest of the area was largely dry. It was a spacious, flat terrain with many rolling hills, well-suited for maneuvering troops.
Chapter 1111