Strategic Background
This was a local climax of the Battle of Dongxing. After taking power, Zhuge Ke rebuilt the Dongxing dike and raised two cities, east and west, flanking it to dam Chao Lake, drawing Wei's attention northward. Wei sent Hu Zun to lead foot and horse across the water by pontoon bridge and encamp on the dike, detaching Huan Jia and Han Zong to storm the two cities; but the fortifications were lofty and strong, and the Wu generals held the heights to the death and would not give battle, so for a time the Wei army found no opening to bite into [c:15919]. The battlefield was thus dragged into stalemate, and the bitter cold and heavy snow further lowered the Wei army's vigilance—this was precisely the window Ding Feng was waiting for.
Dispositions of the Two Sides
The Wei main force was pressed against the dike besieging the two cities, its center of gravity oriented toward the land strongpoints; facing the waterway, Hu Zun deployed only scouts, while the main tent was holding a grand banquet. The Wu vanguard approached from the water with thirty warships, about a hundred men each, a force that seemed limited in scale [c:15919]. This disposition of "land assault as primary, water defense as secondary" caused the Wei army to turn all its attention toward the fortified cities, leaving the water surface a neglected weak flank and creating the conditions for the Wu army to fight a larger foe with smaller means.
Key Decision Point
The deciding move lay in Ding Feng's dual reading of the opportunity and the enemy's psychology. First, he grasped the Wei army's slackness—"seeing the boats few, they grew contemptuous of the enemy, drinking in the snow without preparation"—and declared that the moment to win merit and rank was right then [c:15919]. Second, he made a counterintuitive choice of equipment: ordering his soldiers to strip off armor and helmets and discard their long weapons, carrying only short blades. Heavy armor and long halberds favor arrayed head-on clashes but burden the speed of storming ashore; light gear and short weapons bought the suddenness of landing and the explosive force of close hand-to-hand combat. Seeing the Wu troops remove their armor, the Wei army actually laughed and grew even less guarded [c:15919], falling squarely into this calculation of "feigning weakness to induce contempt, and using light equipment to seize the tempo."
Outcome and Resonance
Once the Wu army had stormed ashore, it beat its drums and hacked wildly; the Wei army, struck suddenly at close quarters, turned from contempt to panicked rout, scrambling across the pontoon bridge until it broke and they fell into the water, trampling one another. This engagement directly tore open the Wei army's disposition on the dike, set the keynote for the overall victory in the Battle of Dongxing, and made the legend of Ding Feng's personal feat of arms. As the turning moment of its parent event, the Battle of Dongxing, it is repeatedly used in the Romance's narrative to depict how "an arrogant army is sure to lose."
Counterfactual Speculation
Had the Wei army on that snowy night maintained basic alertness and kept sufficient reserves for the waterway flank, Ding Feng's lightly equipped storming of the shore would have been suppressed at the landing stage; the limited force of thirty boats could hardly have expanded its gains, and the Battle of Dongxing would likely have continued in siege stalemate, the contest reverting to the track where Wei held the advantage in numbers. Looked at conversely, Ding Feng's success was not mere brute courage but the stacking of the enemy's contempt, the pontoon-bridge dead end of the terrain, and the numbing wrought by the weather into a single annihilating strike—remove any one premise, and this victory of the few over the many would have been hard to reproduce.