Organisation and Equipment

Xu Lun did not discuss the organisation and equipment of his war cart formation in detail, as it was simply adapted from his original square formation. Instead of assigning three Ju Ma (拒馬) to every forty-five infantry, a war cart, which could be a Qing Che (輕車), a Zhan Che (戰車), or some other types, was assigned to every seventy-five infantry. Additionally, a supply cart was given to every twenty-five support personnel. As such, a 3,000-strong army would own twenty-four war carts as well as twelve supply carts. The seventy-five troops unit consisted of twenty-five spearmen, twenty-five archers (including crossbowmen), and twenty-five handgonners.

Cavalry arm of the war cart formation was largely unchanged, although some cavalrymen fought dismounted in the new formation.

Formation and Tactics

Simplified drawing of Xu Lun's new formation. From 'Chou Bian Zuan Yi (《籌邊纂議》)'

Xu Lun's new formation was a square formation with no vulnerable flanks or rear. However, it was much smaller, deeper and more robust, being five ranks deep instead of alternate one and two ranks like the original formation. Its five ranks consisted of spearmen crouching in the first rank, archers and crossbowmen partial squatting in the second rank, handgonners standing in the third ranks, cavalrymen in the forth rank acting as reserve force, and a mix of mounted and dismounted troops in the fifth rank. This allowed all troops in the second, third and forth rank to shoot at the same time.

The formation was in essence a very standard wagon fort, utilising massed projectile weapons to thin down and demoralise the enemy as well as compel them to attack, chained war carts and deep infantry ranks to receive and resist enemy charge, and reserve cavalry to counterattack once the enemy lose the momentum of the charge.

Like its predecessor, this war cart formation also had eight "gates" for the cavalry to move in and out of the square. These specifically prepared gates ensured that no matter which direction the enemy attacked, Xu Lun's cavalry could always move out of the formation through another unthreatened gate to flank or even encroach the enemy.

Shui Di Long Wang Pao (水底龍王砲, lit. 'Underwater dragon king bomb')

Drawing of Shui Di Long Wang Pao, from 'Wu Bei Zhi (《武備志》)'.

Shui Di Long Wang Pao is a drifting naval mine used by the Ming army. Designed for riverine warfare, the mine is usually deployed upriver under the cover of the night, so that it can naturally drift downstream towards moored enemy ships. 

Shui Di Long Wang Pao consists of several components: a four to six catties wrought iron bomb placed inside a lacquered (waterproofed) cow bladder, which is fixed on top of a wooden plank or miniature raft. Several stone weights are tied to the underside of the plank, serving as its ballast. The stones are heavy enough to let the entire mine stays submerged, but not too heavy as to cause it to simply sink to the bottom of the river. An incense fuse inside a waterproofed tube made of goat intestine is connected to the bomb at one end, and connected to a small wooden plank attached with goose feathers at the other end. This is to ensure that the incense stays afloat and dry, as well as having enough air to stay lit.

Despite these waterproofing features, Shui Di Long Wang Pao is still somewhat unreliable. Both the bomb and its fuse are susceptible to underwater debris and unpredictable river currents/waves, not to mention the incense sometimes goes out due to insufficient oxygen.