长驱直入 — “To advance rapidly and irresistibly”

In 219 AD, Cao Cao and Liu Bei were fiercely battling over Jingzhou, a strategic stronghold Cao Cao aimed to seize. Liu Bei's general, Guan Yu, heavily besieged Xiangyang, while Cao Ren, Cao Cao's cousin, resolutely defended Fancheng, a neighboring city to Xiangyang, finding himself in a very difficult position.

That July, Cao Cao dispatched Yu Jin, the General of Tiger Might, to reinforce Cao Ren. Soon after, Fancheng and its surroundings experienced continuous heavy rainfall, causing the Han River to overflow. Guan Yu seized this opportunity to divert floodwaters to inundate Cao Cao's army, resulting in Yu Jin's entire force being annihilated and forced to surrender. With floodwaters surging into Fancheng, Cao Ren's situation became critical.

Some of his subordinate generals advised him to abandon Fancheng and retreat by boat. However, others strongly opposed this, arguing that the floodwaters could not remain high indefinitely and would recede in due course, suggesting that holding fast was the better option. Cao Ren found this reasoning sound and decided to defend Fancheng resolutely.

Not long after, Cao Cao sent another prominent general, Xu Huang, to relieve Fancheng. Xu Huang, a shrewd strategist, did not immediately lead his troops directly to Fancheng. Instead, he encamped at a short distance, then sent men to shoot arrows carrying letters into Fancheng, establishing communication with Cao Ren. Coincidentally, Cao Cao was still organizing other reinforcements, and upon learning of Xu Huang's actions, he highly approved, instructing him to wait for all the various forces to arrive before advancing on Fancheng together.

At that time, a part of Liu Bei's army was stationed in Yancheng, not far from Fancheng. Xu Huang led some of his troops to the outskirts of Yancheng, deliberately digging pits, seemingly intending to cut off the Yancheng army's retreat. The stationed troops fell for the ruse and hastily withdrew from Yancheng. Thus, Xu Huang easily captured the city.

By this point, the twelve columns of troops organized by Cao Cao had arrived. Xu Huang then joined forces with these troops, planning to launch a pincer attack on Guan Yu with Cao Ren.

Guan Yu had troops stationed in two locations: Weitou and Sizhong. Xu Huang feigned an attack on Weitou, but in reality, personally led his main force to attack Sizhong. By the time Guan Yu discovered Xu Huang's true main objective, it was too late. His five thousand troops, who hastily arrived at Sizhong, were quickly defeated by Xu Huang. Subsequently, Xu Huang led his subordinates, making a direct and unimpeded charge into Guan Yu's encirclement of Cao Ren. Guan Yu's soldiers were no match and fled in defeat, finally lifting the siege of Xiangyang and Fancheng.

When Xu Huang's victory report reached Cao Cao, Cao Cao immediately wrote a commendation order and sent it to the front lines. The order stated: "I have been campaigning for over thirty years, and among all the ancient masters of warfare I know, none could '长驱直入' (advance rapidly and irresistibly over a long distance) into the enemy's encirclement like you, riding without pause and pressing straight forward."