Wubei Zhi (Vol. 49)

...defend themselves; only then can we face the enemy invadersoriginal: "lu" (虜). A term historically used in Chinese texts to refer to northern nomadic groups, often translated as "barbarians" or "captives," here used to denote the mobile invading forces of the northern frontier.. Only when there are forts can each person defend themselves. Yin Geng, the Vice Magistrate of Yu County Yu County (蔚) was a vital strategic location in the Ming dynasty's defensive line, located in modern-day Hebei province., composed the "Twelve Articles of Fortification Regulations." His words are truly practical. I have specifically selected the systems and diagrams from his complete book; even those parts that have appeared elsewhere in this work I did not wish to delete.

Article 1: Establishing the Fort

Regarding the establishment of a fort: the difficulty lies not in the lack of a place to build, but in the difficulty of placing it in the right location. With hills and mountains to the left and rear, and rivers or marshes to the right and front—in ancient times, no army would march without first selecting the terrain. How much more important is this for a fortified settlement where people must live? Therefore, the first regulation concerns the placement of the fort. It contains four sub-points.

First: Relying on Heights. "Heights" refers to landforms such as mounds, hills, and mountain ridges. Building a fort in reliance upon such features is advantageous for creating defensive obstaclesoriginal: "she xian" (設險). This refers to the strategic use of natural geography—such as cliffs or steep slopes—to make a position difficult for an enemy to approach or attack.. However, while some heights are suitable to rely on, others should be avoided. If the four sides are wide and open, and the cliffs stand as sheer as walls, then it is suitable. But if the interior is low and the exterior is highoriginal: "nei bei wai gao" (內卑外高). A disadvantageous position where the enemy on the outside occupies higher ground than the defenders inside the walls, allowing the enemy to see and fire down into the fort., or if there are overlooking...