Wubizhi Volume 103: Military Equipment and Logistics – Defense – Forts 1

41. Enclosure Walls

Once the site for the fort has been secured, the design of the enclosure walls must be discussed. There are no strict limits on size, and one should not be constrained by a need for perfect straightness. The primary goal is simply to ensure the interior is large enough to contain the local population, while the exterior remains far enough from any high ground that might allow an enemy to look down upon or press too closely against the defenses.

However, a large fort is not as effective as a small one; a smaller perimeter is inherently sturdier. Likewise, straight walls are not as effective as curved ones, as curves are easier to defend. For this reason, the Founding Ancestor of the Song dynasty Emperor Taizu (r. 960–976), known for his military pragmatism. used his brush to smudge the straight lines on Lord Zhao of Han’s Zhao Pu, a prominent chancellor and strategist. city map, intentionally preventing the walls from being perfectly straight. Later, when Nianmohe Wanyan Zonghan, a formidable general of the Jurchen Jin dynasty. of the Jin viewed the city of Bian Bianjing, the capital of the Northern Song, modern-day Kaifeng., he immediately remarked that its straight layout made it easy to attack.

Furthermore, the wall standards of the ancients usually followed a formula: a height of five zhang Approx. 50 feet or 15 meters., a base width of two zhang five chi Approx. 25 feet., and a top width of one zhang two chi five cun Approx. 12.5 feet.. In modern civilian forts, however, the height is generally only one zhang five chi Approx. 15 feet., which increases to two zhang Approx. 20 feet. when adding the parapets original: "陴倪" (pí ní); the low, notched walls on top of the main rampart for protection.. The base width is usually a bit over one zhang, and the top width is only five or six chi.

If the wall is too low, arrows and stones can easily reach the defenders, and the parapets become difficult to maintain. Recently, when the barbarians original: "虜" (lǔ); historically referring to northern nomadic forces such as the Mongols or Manchus. attack forts, they use many "flying stones" to knock down these parapets. Once the parapets are gone, men do not dare stand upright upon the wall, and the enemy subsequently swarms like ants original: "蟻附" (yǐ fù); a standard military term for scaling walls using ladders. to climb over. The current system for walls...