BigBoard Gaming · monthly series · publishes September 2026
1. The Strategy
The sixth of the Hundred Unorthodox Strategies is the simplest to state and the easiest to botch: commit your mobile arm only where it can move. “Whenever cavalry units engage infantry,” the text runs, “should they encounter mountains, forests, ravines, defiles, bodies of water, or wetlands, they must urgently proceed through them and quickly depart. These six constitute terrain on which defeat is certain.” Fight instead on “level, easy terrain where the cavalry will be unobstructed in both advancing and retreating.” The maxim: “Employ cavalry on easy terrain” — 易地則用騎. (Sawyer’s translation.)
The virtue of cavalry is not its sword; it is its speed the freedom to advance, wheel, and retire faster than the enemy can react. Strip that away with broken ground and you are left with expensive men on tired horses, fighting infantry on the infantry’s terms.
The text’s example is a masterclass in not taking the bait. In 910–911 CE the Jin general Zhou Dewei faced the Liang army of Wang Jingren. His king wanted to attack at once; Zhou refused primarily because the ground was closed, and on closed ground the Jin cavalry advantage would revert into a liability. He talked the king into withdrawing to open country, then spent the winter raiding the Liang supply lines rather than charging. By spring, at Boxiang, the Liang army was starving and worn; when Wang Jingren’s own troops shifted and the rest assumed he had fled, the whole force collapsed only then did Zhou loose three thousand elite horsemen to finish the war. He won by choosing the ground and the moment, not the fight.
2. Eastern Wisdom
Sun Bin; Sun Tzu’s descendant and in fact the sharper tactician of the two, states the same rule from the other side. Terrain is what strangles the mounted arm: “three li of swamp will obstruct troop movements … [and] bog down … mounted troops. The movement of troops is obstructed through a poor choice of terrain” (Sun Bin: The Art of Warfare, p.10).
[Side note: almost nobody’s heard of a “second Art of War”: Sun Bin’s text was lost for ~2,000 years and only rediscovered in 1972, in a Han tomb at Yinqueshan (Shandong), on bamboo strips. Don’t panic I’m not hallucinating, my quotes, it’s just obscure enough that the name-twin surprises. ] Elsewhere he sorts the whole army by ground chariots to the flattest fields, cavalry to rougher going, crossbowmen into the defiles that close on both sides (p.24). The through-line across five centuries of Chinese thought: the arm and the ground are a single decision, never two.
3. A Western Mirror
The West reached the same law by a different road and gave it an engine. What Zhou Dewei’s horsemen were, Guderian’s panzers became the cavalry of the machine age, bound by the identical rule. Robert Greene calls it the now well worn Blitzkrieg strategy: “overwhelm resistance with speed and suddenness,” strike “before your opponents have time to think” (The 33 Strategies of War, pp.13–14). Napoleon built a career on it, at Jena his corps moved with “astonishing speed and mobility” while the Prussians “argued and dithered” (p.75). But the machine changed nothing about the terrain: armor that ran wild across the plains of France and the Russian steppe crawled and died in the bocage of Normandy, the rubble of Stalingrad, the forests of the Hürtgen. Easy terrain for the tank, exactly as for the horse. We can of course trail this all the way back to Alexandrian days, and the Roman era. Its not just tanks.
On the table: every decent wargame enforces this in its terrain chart. Cavalry and armor pay movement and combat penalties in woods, marsh, and mountain, and forfeit their charge or overrun on anything but clear hexes, while the same rough ground hands the defender a multiplier (in the SCS Fallschirmjäger game I’m playing now, a village triples the defense). The rule for the counter is the rule for the horse: never commit your mobile arm to ground that cancels the one thing it exists to do. Save it for the clear terrain, the open flank, the pursuit. Games that bonus Cavalry or Armor in open ground are doing their best to be authentic and true to the capability. Often is a 1.5 or 2.0X on their combat values such as OCS does. Other times it is built into the combat strength like Stalingrad ’42.
4. Sun Tzu vs Clausewitz
Beneath the terrain maxim sits a deeper agreement. Sun Tzu and Clausewitz both hunt “the quickest and most decisive victory,” won through “absolute superiority at the decisive point of contact” (Handel, Masters of War, p.38); for Clausewitz the supreme requirement was “the maximum concentration of troops at the critical point of contact” (p.51). “Employ cavalry on easy terrain” is that idea in miniature put your shock arm where the ground lets it deliver overwhelming force at the moment of collision, for maximum effect.
They part on how to say it. Sun Tzu hands you the rule, finished, to be accepted and applied detailed and specific; avoid these six terrains, use cavalry there. Clausewitz distrusts the neat rule; he “never tries to establish specific force ratios” (p.43), keeping his analysis on a “higher methodological and philosophical plane,” a process of questioning rather than a checklist (p.10). Sun Tzu gives the commander a card to keep in his pocket; Clausewitz gives him the habit of mind that would generate the card himself. On easy terrain, both would send in the horse.
Series Note
Post #6 of 100. Next: Strategy #7 — Amphibious Strategies (舟) — publishes October 2026.