Du Rui 杜睿

In Chapter 102 of the Romance, Zhuge Liang, having defeated Sima Yi's raid on his camp and returned, has Zheng Wen, who had feigned surrender, beheaded and confers on a plan to take the land south of the Wei River. When the Wei army will not come out to meet him, he rides in person in a small carriage in front of Mount Qi and along the east and west of the Wei River to survey the terrain, and comes to a valley shaped like a gourd, able to hold more than a thousand men inside, and enclosed behind by two hills so that only one man and one horse can pass at a time. The guiding officer answers that this is Shangfang Valley, also called Hulu Valley. Romance, Ch. 102 §30 · 37 · 39–40

Zhuge Liang returns to his tent, summons the two subordinate generals Du Rui and Hu Zhong and whispers a secret plan in their ears. He has the more than one thousand craftsmen accompanying the army sent into Hulu Valley to build wooden oxen and gliding horses, and has Ma Dai guard the mouth of the valley with 500 troops, charging him not to let the craftsmen out or outsiders in, since the plan for capturing Sima Yi rests entirely on this undertaking and word of it must on no account leak out. Romance, Ch. 102 §40–41

Du Rui and his companion supervise the craftsmen inside the valley and have them build according to the prescribed method, while Zhuge Liang comes and goes every day to give instructions. One day, when the Chief Clerk Yang Yi reports that the provisions are all at Jiange and are hard to transport with laborers, oxen and horses, Zhuge Liang says that he has had wooden oxen and gliding horses built, which neither drink nor eat and can carry loads day and night, and he writes out the method of building them on paper with his own hand to show them. In the Romance, Du Rui's name appears only in two passages of the Hulu Valley scene. Romance, Ch. 102 §40–43