Although Li Yu repeatedly told Zheng and Du to advance by land and water and cooperate with each other before setting out on the expedition, after receiving the news that the Chizhou Navy had been completely wiped out and that Yang Shu and Sun Zhen's troops had also been lost, Zheng Yanhua, who led the Jiangnan Navy, was terrified. Not only did he not move his army forward, but he ignored Du Zhen's troops, who had already begun contact with the Zhou army, and ordered the fleet to retreat ten miles, completely out of the battlefield east of Quarry Rock.

Seeing that Zheng Yanhua's troops suddenly withdrew from the battlefield, ignoring how to signal and raise the command flag on his side, Du Zhen knew that the "good brother" who had made an alliance with him before the expedition and vowed to live and die together and advance and retreat together had already broken his oath and abandoned his oath, and he could only fight alone against the enemy this time.

Although the tragic end of the annihilation of the entire army of Yang Shu and Sun Zhen was just around the corner, and their own troops were only half of the opponent's, and there was a world of difference in weapons and equipment, Du Zhen, who was loyal to the Jiangnan Imperial Court and grateful to Li Yu, was not afraid of fighting and avoiding the enemy like his "good brother", but held the belief that "knowing that there are tigers in the mountains, and preferring to go to the tiger mountains" and "the general should be a horse leather shroud", he lined up the whole army in front of the Zhou army's blocking position at the fastest speed, and then took the lead and led 15,000 soldiers to rush forward. So, on the fourth day after the annihilation of the entire army of Yang Shu and Sun Zhen, the land in Jiangkou Village, twenty miles east of Quarshiji, was once again soaked in blood. Du Zhen and his 15,000 soldiers were all killed under the heavy fire of the Zhou army, except for 2,000 who were captured and 1,000 escaped.

Originally, according to Zeng Zhilin's original intention, a general like Du Zhen who was both loyal and daring to take responsibility was worthy of respect and protection. Therefore, before the battle began, he ordered the artillery fire on land and on the river not to shoot at the place where the commander of the Jiangnan Army was located, and asked the infantry and cavalry not to rush to attack and encircle and annihilate the enemy, especially the unit where the commander of the enemy army was located, when surrounded by his own side, but to persuade him to surrender as much as possible and capture this Du Zhen alive as much as possible. What Zeng Zhilin didn't expect was that Du Zhenhui would take the lead in order to boost the morale of his soldiers, and he led his own soldiers and generals to rush to the front of the Jiangnan Army with a handsome banner. Since Zeng Zhilin's order to the infantry and cavalry was to salute the Jiangnan army, especially the troops where his commander's banner was located, rather than at the beginning of the battle, after the battle began, Du Zhen and his personal generals avoided the shelling because the Zhou artillery deliberately avoided them when firing, so they became the preferred target of the infantry in the defensive position. When he led his descendants to rush to about 150 paces away from the defensive position of the Zhou army's infantry, they were met with heavy and light machine gun and rifle fire. However, in just a few breaths, Du Zhen and nearly 300 of his pro-soldiers were all beaten into a "hornet's nest", and none of them could insist on rushing to within 100 steps.

Knowing that Du Zhen died on the way to the charge, Zeng Zhilin was very sorry and regretted that he had no chance to meet and intersect with such a fierce general. After the battle, he ordered the soldiers who were familiar with Du Zhen among the captives to look for Du Zhen's body at the location of the Jiangnan Army Marshal's Banner, put it up, and put it into the ground for peace; On the one hand, he submitted a report to the committee, hoping that the Later Zhou court would recognize a loyal man like Du Zhen after the war, whether he protected the Later Zhou or Jiangnan. Zeng Zhilin's proposal was first approved by Wang Kunjun and Xu Shao'an, and then discussed by the committee, and was finalized in the form of a resolution, which was put into effect after the war was over.

Du Zhen died in battle, and his 15,000 men and horses were almost wiped out, Zheng Yanhua, who got the news, felt a little guilty in his heart, but also deeply believed in his decision to take the initiative to retreat to avoid the battle, and the war spirit in his heart became weaker and weaker, and finally contributed to his idea of fleeing the battlefield and withdrawing to Jinling.

It's a pity that Zhou Jun didn't give him this opportunity. Just when Zeng Zhilin led his troops to annihilate Du Zhen's troops on the shore, he secretly rushed to the sea from Jinghu before the war, and at this time, he led the "Flying Dragon Army" Navy Southern Expeditionary Fleet to join the First Fleet of Jiangfang, and Xin Feiyu, who served as the commander (commander-in-chief) of the Southern Expeditionary Naval Army, was not idle. After discovering that the Jiangnan Navy did not advance but retreated, and retreated ten miles at once, Xin Feiyu gave an order, and the mixed formation composed of the Southern Expeditionary Fleet of the "Flying Dragon Army" Navy and the First Fleet of the Great Zhou River Defense rushed towards Zheng Yanhua's headquarters in the wind and waves.

Seeing the warships of the Zhou army rushing towards him at a high speed, Zheng Yanhua was terrified, and he didn't care about how to explain to the lord of the country after returning to Beijing, so he hurriedly ordered the warships to turn around and retreat in the direction of Jinling. As the so-called "the courage of the soldiers", the generals are as stable as Mount Tai and confident, and the soldiers under them will also become calm and confident; For the generals to panic and fear the enemy, the soldiers under his command will naturally be panicked and have no fighting spirit. Therefore, when Zheng Yanhua ordered a retreat and commanded his ships to flee downstream first, the morale of the soldiers and generals on thousands of warships under his command plummeted as their commanders fled. Everyone pulled anchors and hoisted their sails, chasing after their boss and fleeing.

For a time, the Jiangnan naval army began to scramble to turn the bow of the ship, collide with each other, and grab each other's way, and the originally wide river was instantly blocked by these warships, and it was crowded and chaotic. As a result, the original unintentional collision turned into an intentional collision, and the original rush by relying on boat manipulation technology turned into swords and guns, bows and crossbows fired at each other, and some huge warships fled in order to open a way for themselves, and began to rampage on the river, and even ran directly over the small warships, completely ignoring the fact that there were also their comrades in robes.

However, Yiqiē's efforts were in vain. From the moment Zheng Yanhua hastily ordered a retreat, the fate of this Jiangnan naval army, which had thousands of large and small warships and 15,000 soldiers, was already doomed. The chaotic and disorderly retreat caused most of their warships to be clogged up on a stretch of river about three or four miles long, and became a live target for the Zhou warships that swooped down like tigers.

Compared with the First Fleet of Jiangfang, the Southern Expeditionary Fleet from the "Flying Dragon Army" Navy was far superior in terms of the size of the warships and the caliber of the guns equipped on the ships, and was not above the same level. Although the number of guns of the six "Flying Dragon Army" Haijiao-class light cruisers, which are nearly twice as large as the capital ships of the First Fleet of Jiangfang, has not increased much, the minimum caliber of their guns is the same as the maximum caliber of the latter's guns, and their firepower is not the same. It is precisely because of the addition of the "Flying Dragon Army" Navy's Southern Expeditionary Fleet that the water battle of Quarry Rock, which was much larger than the previous Wuchang Water Battle and Chizhou Water Battle, lasted for a shorter time than the previous two water battles. In the face of the fierce bombardment of the 130mm and 105mm guns of the Haijiao-class light cruisers, the warships of the Jiangnan Navy were sunk in pieces, or became a blazing torch. In just half an hour, the originally crowded and immobile river suddenly became clear, except for 100 small and medium-sized warships that were lucky enough to escape the shelling, and a few wrecks of warships that were still burning and sinking slowly, the other ships of this Jiangnan naval force either sank into the river or turned into broken wood and floated on the river, never blocking the channel again.

Among the sunken warships, Zheng Yanhua, who was the first to escape, but became the preferred target of the Haijiao-class light cruiser, was directly hit by two 130mm shells and instantly turned into fragments. Because more than a dozen 130mm shells came one after another, Zheng Yanhua himself and the 500 soldiers on the ship were all buried in the belly of the fish, and none of them survived. Of course, the losses of the Jiangnan Navy were by no means limited to these 500 people. In this battle, the Jiangnan Navy sank 910 large and small warships, lost more than 12,500 soldiers, and more than 130 small and medium-sized warships and 2,500 soldiers were captured. It's just that, unlike Du Zhen and his more than 10,000 soldiers who died tragically and heroically, and were admired by Zeng Zhilin and even the entire Southern Expeditionary Army, the death of Zheng Yanhua and his 12,500 soldiers and generals seemed to be both wretched and pitiful, and was despised.

On April 28 of the lunar calendar of the second year of Jianlong, after leaving the four divisions and three regiments of the "Flying Dragon Army", the four regiments of the "Security Army" and some warships of the First Fleet of Jiangfang to guard the pontoon bridge, the southern expeditionary army was divided into two routes. The Left Route Army (all of the East Route Army and the Second Regiment of the Fourth Division of the Middle Route Army) was led by Wang Kunjun and Xu Shao'an, and went northeast from Quarry Rock to Jinling along the Yangtze River; The Right Route Army (the rest of the Western Route Army and the Central Route Army) was led by Zeng Zhilin, turned eastward, and after clearing Lishui, Jurong and other peripheral prefectures and counties, and receiving the Southern Route Army from the southeast, it turned around and headed west, and joined the Left Route Army under Jinling City.