“When Rong’er was alive, she told me that epidemic poison is extremely dangerous, and only pits deeper than one zhang can completely isolate the epidemic poison.”

Li Yuanji nodded, “This time, sister-in-law truly helped us greatly. Otherwise, we would have been trapped to death in Luoyang by Li Shimin.”

Li Jiancheng’s eyes were cold as he said, “Since Rong’er married me, she has always thought of me and schemed for me everywhere, yet she died tragically at the hands of Li Shimin and Zheng Shi. This revenge, I will definitely collect with interest!”

“Big brother, rest assured, I will definitely help you take revenge!” After a pause, Li Yuanji asked curiously, “Big brother, do you think they will guess that this epidemic poison was released by us?”

Li Jiancheng smiled coldly, “Even if they guess, what can they do? Can they neutralize the epidemic poison? At most, they’re just struggling on their deathbed.”

“That’s true, but after all, Li Shimin has Chang’an as backup. Perhaps he has already sent people back to Chang’an to transfer troops. If reinforcements arrive, that would be troublesome. So in my opinion, the counterattack should be sooner rather than later. As long as we control Li Shimin, we control the entire Great Tang.”

Li Jiancheng bowed his head in thought for a while, then said, “You’re right, the longer we delay, the more complications may arise. However… before that, we must do one thing first.”

Li Yuanji blinked, “What thing?”

Li Jiancheng leaned close to his ear and whispered. After listening, Li Yuanji immediately laughed, “Big brother is still brilliant. Good, I’ll go arrange it now!”

“Tell them to be careful and not let anyone see through the deception. If everything goes smoothly, the day after tomorrow will be when we counterattack!”

Everything proceeded silently. That night, the first person to die from the epidemic appeared in the Tang army camp. The death was extremely horrific, with blisters covering the entire body, making it unbearable to look at directly.

Du Ruhui found several trusted men who had drunk the medicinal soup, wrapped the corpse in white cloth, and carried it to the deep forest for burial. After filling in the last shovelful of earth, those soldiers came before Du Ruhui, “General, it’s been buried.”

Du Ruhui spat out the wild grass in his mouth, enduring the bitterness in his mouth and tongue, “Thank you for your hard work. Go back and rest. Remember, don’t say anything.”

“Yes.” The soldiers responded and headed toward the military camp. One of the personal guards deliberately slowed his pace and walked alongside Du Ruhui.

Du Ruhui looked at this personal guard who had followed him for six years, “What is it? Do you have something to say to me?”

The guard’s expression was complex as he said, “General, people in the army have already begun to suspect this is an epidemic. Even if we don’t say anything, I’m afraid it can’t be concealed much longer.” They were among the few who knew the truth.

Du Ruhui wiped his face and said heavily, “I know, but this matter absolutely cannot be made public right now.”

“Haven’t the two physicians found a way to treat the epidemic yet?” Faced with the guard’s words, Du Ruhui sighed, “Epidemics are difficult to cure, especially when the army lacks medicinal materials.”

The guard was silent for a while, then said worriedly, “But if this continues, sooner or later there will be trouble because it can’t be concealed, and more and more people will die. General, you must quickly think of a way to stop things from getting worse.”

Du Ruhui smiled bitterly, “Sir Liu and I think of solutions day and night, but we really can’t come up with any. We can’t even find where the source of the epidemic is!”

Hearing this, the guard was also helpless, “Following the General’s instructions, I’ve inquired both openly and secretly several times, and indeed found nothing suspicious. If I had to say what they have in common, it would be attacking Luoyang City.”

He said this casually, but it made Du Ruhui’s heart skip a beat as he remembered something they had always overlooked. Could it really be this?

The more Du Ruhui thought about it, the more possible it seemed. After returning to the military camp, he went to the tent where the sick soldiers were isolated, then rushed at top speed to Liu Hongji’s tent. Upon seeing him, he immediately said, “Sir, I know!”

Liu Hongji put down the medical book in his hands, “What does the General know?”

“The source! The source of this epidemic!” Hearing this, Liu Hongji immediately perked up and urgently prompted, “Speak quickly!”

Du Ruhui calmed his breathing from the rush, “The first batch to fall ill were all wounded soldiers who had attacked Luoyang under His Majesty’s command and barely survived on the battlefield.”

Liu Hongji nodded, “That’s right, but what of it?”

“This is their common point, and the next batch of soldiers to fall ill also had a common point – they were responsible for rescuing the wounded soldiers. A coincidence?”

Liu Hongji frowned for a moment, “The General thinks the source of the epidemic was that siege battle?”

“Exactly!” Having answered thus, Du Ruhui continued, “And His Majesty, Sir, do you remember what His Majesty did after the siege battle ended?”

Liu Hongji was stunned, then his face turned ugly, “His Majesty personally went to help the wounded soldiers.”

“Exactly, this is why His Majesty contracted the epidemic while you and I are fine. I’m certain that the epidemic outbreak is inseparable from that previous siege battle!”

“I was just reading medical books and have some understanding of how epidemics appear and even break out. A siege battle alone could never trigger an epidemic, unless…”

“Unless it was man-made!” Du Ruhui spoke these five words one by one.

Liu Hongji’s expression was serious, “You think it was Li Jiancheng?”

“Besides him, I can’t think of a second person.” Du Ruhui’s answer was also what Liu Hongji was thinking. But no matter how sinister and cunning Li Jiancheng was, no matter how unscrupulous his methods, he was ultimately just a mortal. How could he control natural disasters, unless… like the poison in the Qi River, it was all man-made!

Liu Hongji thought while saying, “I remember that day when we went to question the infected soldiers, they all said they had been hit and wounded by stones shot from catapults. Others were the same – either stones or crossbow bolts. That is to say, the problem very likely lies with those two things!” Before he finished speaking, he had already rushed out of the tent, with Du Ruhui following closely behind. They both had the same thought.

Physician Jiang had been working day and night for several days and finally planned to get some sleep. Just as he was about to lie down, he was pulled out by Liu Hongji, with no time even to bring a lamp, walking in the pitch-black night until Du Ruhui brought a torch, finally providing some light.

Physician Jiang asked puzzledly, “Sir Liu, General Du, where are you two taking me?”

Liu Hongji glanced around and lowered his voice, “We may have found the source, but to be cautious, we still need Physician Jiang to take a look.”

Hearing this, Physician Jiang immediately lost all sleepiness and quickly followed behind them until they stopped at a place only dozens of zhang from Luoyang’s city gates.

Du Ruhui used the torch’s light to find several stones and crossbow bolts abandoned on the battlefield, “These should be them.”