Nope, it isn't Lu Xun of the Southland, but Lu Xun of the Riverlands! Lu Xun, though a very minor commander in SGYY, grabbed my interest the very first time I read the novel. His bio was very easy to write, but I felt that he deserved some recognition for his achievements that, though not towering, were certainly not menial. I hope everyone enjoys reading it as much as I did writing it.
It's not false advertising, really.
Lu Xun was a general serving the Riverlands during the Second Emperor, Liu Shan’s, reign.
When Sima Zhao began his expedition against the Riverlands, Zhong Hui was put in charge of the capture of Hanzhong. Lu Xun was in charge of the defence at Nanzheng Pass, and Xu Yi, the vanguard general of the forward contingent in Zhong Hui’s army, attacked the pass as soon as he arrived. Lu Xun, however, had been forewarned of Xu Yi’s advance, and had hidden soldiers armed with the repeating crossbow Zhuge Liang had created under the bridge leading to the pass. (1) When Xu Yi and his men reached the pass, Lu Xun set off his ambush with signal-sticks, and the northern army was defeated and forced back, suffering many casualties from the repeated bolts of stones and arrows.
Zhong Hui later arrived to lead a renewed attack on the pass, but Lu Xun had already reorganised his troops and drove back the northern force once more with fresh volleys of arrows. Zhong Hui attempted to retreat, but Lu Xun raced down from the pass with five hundred men. Zhong Hui tried desperately to escape, but as he crossed the bridge, the earthen surface gave way, snagging his horse’s hooves and nearly throwing Hui from his horse. His mount unable to move, Zhong Hui dismounted and attempted to flee on foot, but Lu Xun came charging after him, spear stabbing numerous Wei soldiers in his path. Zhong Hui would have fallen to Lu Xun’s onslaught if not for Xun Kai, a Wei soldier, who turned and shot Xun from his horse. The Wei soldiers, on Zhong Hui’s orders, regrouped and led a renewed assault on Nanzheng pass - Lu Xun’s men refrained from shooting down on the enemy for fear of hitting their own comrades. Nanzheng was thereupon lost and Lu Xun killed. (2)
1: The repeating crossbow Zhuge Liang had created could fire ten eight-inch arrows at a time. Zhuge Liang had created the sketches for the crossbow but died before seeing it built. The sketches were passed on to Jiang Wei, who undertook the production of the weapon.
2. There is no actual mention of Lu Xun’s death in SGYY - the arrow shot by Xun Kai may very well have killed him, but without any clarification in the novel, one can only speculate.