[Meaning]: This idiom is used to describe an army advancing forward with unstoppable momentum, penetrating deep into the enemy's heartland.
[Origin]: The idiom originates from Cao Cao's "Imperial Edict Rewarding Xu Huang": "I have commanded troops for over thirty years, and among all the ancient masters of warfare I have heard of, none have ever driven straight into the enemy's encirclement as you have."
In the year 219 AD, Cao Cao fought fiercely with Liu Bei to seize Jing Province, a strategically vital location. Liu Bei's general Guan Yu heavily besieged Xiangyang, while Cao Cao's cousin Cao Ren held firm in Fancheng, adjacent to Xiangyang, putting him in a difficult situation.
That July, Cao Cao dispatched General Hu Wei, Yu Jin, to reinforce Cao Ren. Soon afterward, heavy rains fell continuously in the Fancheng area, causing the Han River to flood. Guan Yu seized the opportunity to channel the floodwaters to inundate Cao Cao's army, resulting in Yu Jin's entire force being destroyed and forced to surrender.
Due to the floodwaters breaching Fancheng, Cao Ren's situation became critical. Some of his officers advised abandoning Fancheng and retreating by boat. However, others strongly opposed this, arguing that the floodwaters could not remain so high indefinitely and would recede in time, so it was better to hold out. Cao Ren found this reasoning sound and decided to continue defending Fancheng.
Soon, Cao Cao sent the general Xu Huang with another army to lift the siege on Fancheng. The experienced and shrewd Xu Huang did not march his troops directly to Fancheng. Instead, he stationed them at a slightly more distant location, then sent a letter into Fancheng via a hidden arrow to establish contact with Cao Ren. Coincidentally, Cao Cao was still organizing additional reinforcements. Upon learning of Xu Huang's actions, he strongly approved, instructing Xu Huang to wait until all reinforcements arrived before advancing together on Fancheng.
At that time, part of Liu Bei's army was stationed in Yan City, not far from Fancheng. Xu Huang led a portion of his troops to the outskirts of Yan City, deliberately digging pits as if to cut off the garrison's retreat route. The defenders fell for the ruse and hastily evacuated Yan City. Thus, Xu Huang easily captured the city.
By now, the twelve divisions of reinforcements organized by Cao Cao had arrived. Xu Huang joined forces with them, planning to launch a coordinated attack with Cao Ren from inside and outside to strike Guan Yu.
Guan Yu had stationed troops at two locations: Weitou and Sizhong (zhong). Xu Huang pretended to prepare an assault on Weitou, but in reality, he personally led his main force to attack Sizhong. By the time Guan Yu realized Xu Huang's true target, it was too late. The 5,000 troops hastily sent to Sizhong were quickly defeated by Xu Huang. Then, Xu Huang led his troops straight into Guan Yu's encirclement around Cao Ren. Guan Yu's soldiers were routed and fled, and Xiangyang and Fancheng were finally relieved.
When news of Xu Huang's victory reached Cao Cao, he immediately wrote an imperial edict of commendation and sent it to the front lines. The edict read: "I have commanded troops for more than thirty years. Among all the ancient masters of warfare I know of, not one has been able to drive such a long distance without pause, galloping straight ahead and charging into the enemy's encirclement as you have."