When Lu Bu was plotting against Chen Deng, Chen Deng was in fact plotting against Lu Bu as well.
The reason was that the Chen father and son had always wanted to drive Lu Bu out of Xuzhou.
Since Lu Bu had exiled him to Guangling last year, Chen Deng had gathered the troops of the local powerful clans and incorporated the forces under his uncle Chen Yu, giving him more than ten thousand soldiers.
Having gained troops, Chen Deng had intended to make some moves, but neither Cao Cao nor Liu Bei had any intention of taking Xuzhou.
Thus, Chen Deng had quietly been building up his strength, waiting for an opportunity to help Liu Bei break Lu Bu.
Unexpectedly, before Liu Bei could march into Xuzhou, he received news that Lu Bu was preparing to head south and launch a surprise attack on Liu Bei.
Faced with this situation, he wanted to send troops to aid Liu Bei, yet felt that the time was not right.
But if he did not send troops, he feared that Lu Bu might gain an early advantage and put Liu Bei in grave danger.
After turning the matter over and over in his mind, unable to make a decision, he sent for Xu Xuan and Chen Jiao to discuss it.
"Now, I have accepted Lord Xuande's entrustment to guard his rear and prevent Lu Bu from heading south."
"Originally, Lu Bu was allied with Lord Xuande and should not have launched a major southern offensive!"
"Yet that man has broken faith and abandoned righteousness, leading his army south."
"Though I have sent word ahead, I cannot ensure that Lord Xuande's reinforcements will arrive in time. I intend to stop Lu Bu here first. Do either of you have a good plan?"
Xu