After the end of the Hue Campaign in March, the Nguyen regime of South Vietnam collapsed with the fall of Hue City, and the main purpose of Hai Han's troops was also completed.

Although the Nguyen regime has fallen, this does not mean that the areas previously ruled by him will immediately change their names and follow the North Vietnamese court. For example, in a large city like Gwangji, the defenders of the city still chose to resist militarily rather than surrender. However, the North Vietnamese army's combat capabilities, especially the ability to attack large cities, were far from being comparable to those of the Hai Han militia.

Before going south to attack Hue City, the North Vietnamese army had already surrounded Quang Tri, but in order to prevent Hai Han from monopolizing Hue City, the North Vietnamese general Zheng Bai still chose to lead the main force south to attack Hue first, and then turn back to solve Quang Tri. However, although Hue fought relatively smoothly, after the war, it had to divide a part of the army to stay in Hue, first, to guard more than 10,000 South Vietnamese prisoners of war, second, to maintain the local post-war social order, and third, to capture those South Vietnamese officials and dignitaries who were still hiding somewhere in the city.

By the time Zheng Bai had arranged these tasks, it was already late April, and then Zheng Bai waved his army north and began to attack Guangzhi. However, the battle was not as smooth as he had expected, and the defender of Quang Tri City was the son-in-law of Nguyen Phuc Nguyen Nguyen Nguyen of South Vietnam, who had no intention of surrendering at all, but took advantage of the fact that when the North Vietnamese army went south to besiege Hue, he launched several active attacks on the North Vietnamese army outside the city, although it was not able to achieve a breakthrough, but it also caused large casualties to the North Vietnamese army. When Zheng Bai returned to the outside of Quang Chi City with a large army, the North Vietnamese army that stayed here to surround Quang Chi City had already lost nearly a quarter, and if it dragged on for another ten days and half a month, maybe it would really be broken out by the South Vietnamese army in the city.

Compared with the Haihan militia, the biggest shortcoming of the North Vietnamese Army in terms of combat power is that there is too little artillery, and this directly leads to the fact that the North Vietnamese Army has relatively few means in siege warfare, and can almost only rely on more primitive siege methods to operate. On the other hand, the South Vietnamese army in the city. Because there is no way back, the generals have the determination to fight to the death, and the will to fight is no worse than the attacking side outside the city.

After two days of confrontation between the two sides inside and outside the city, the North Vietnamese army launched an offensive. However, due to the lack of long-range firepower, this old-fashioned method of attacking the city by climbing wooden ladders by soldiers did not achieve good results, and the offensive of the previous days had no substantial gains at all except for the cost of thousands of lives in vain.

Of course, Zheng Bai was not interested in slowly grinding down with the defenders under Guangzhi City. Because at this time, their food supply had to rely on Haihan's ships to transport it from the sea. Every day the war dragged on, the North Vietnamese court had to pay nearly 1,000 taels of freight for hiring these ships, which was by no means good news for the North Vietnamese army, which was currently strapped for military spending.

Zheng Bai didn't quite understand how the Haihan militia had destroyed the two inner and outer walls of Hue until this time, because he also used artillery to bombard the city walls of Quang Tri City, but the effect was obviously far from the collapse of the city walls. In the end, he could only attribute this to the fact that the Haihan people still had some secret tactics in their hands that were not disclosed to North Vietnam, although they guessed that they were not far from ten, but this had no practical effect on the current war situation, so he still had to use the most traditional siege method to attack Quang Zhi City.

Under Zheng Bai's strict supervision, ten days later. The North Vietnamese army finally breached the north gate of Quang Tri City, and then spent four full days clearing the city of South Vietnamese remnants. After the city was broken, all the captured South Vietnamese generals were beheaded outside the north gate, and more than 3,000 prisoners of war were also packed and concentrated under the orders of Zheng Bai, ready to be exported to the Haihan people to mortgage war debts.

This battle took the North Vietnamese army half a month, with more than 2,000 casualties, which was several times greater than the loss of Hue City. This result also made the North Vietnamese generals more aware of the gap with the Hai Han militia - thousands of troops crossed the sea to attack Hue. Only one or two hundred people were killed before and after, and they took the fortified city of Hue in one fell swoop.

Originally, this theory was only popular among some officers who had received direct training from the Haihan, believing that the military theory and armed level of the Haihan people had reached the peak, and that if Annam wanted to become strong, it could not do without the support and help of the Haihan. And after the two battles of Hue and Quang Tri. Rather than continuing to be hostile and wary of Haihan, it is better to take advantage of the good relations between the two countries and the formation of various strategic alliances to learn more military things from them, so as to strengthen Annam's military strength.

Of course, this effect is exactly what the Haihan Executive Committee expects. In the past two years, so much energy has been spent on supporting and training North Vietnamese military personnel, so that one day it can influence the direction of military development in Annam. If those in power in the military are inclined to rely on Haihan, arms exports and military training alone will be enough for Haihan to make a lot of money from Annam in the next few years.

After the army led by Zheng Bai pacified Quang Tri, it was too late to take a long-term rest, so it soon went south again, because there were still thousands of miles of territory and dozens of towns south of Hue, waiting for the army to go and receive them one by one. It is said that the army of the Champa State has been somewhat advanced, and after defeating the South Vietnamese army a few months ago, it is still continuing to expand the scope of control to the east, and there is a great posture to take back all the territory of the Champa a hundred years ago.

Of course, Zheng Bai also knew that the Champa side also received some military assistance from the Haihan people, so he did not hope that the remnants of the South Vietnamese army would be able to stop these already armed Cham troops. The only solution to the problem was to lead the army south and keep the Champa army out of the country.

Zheng Bai was anxious to move south to control the situation, but many things could not be done if he wanted to, and the logistical supply problems faced by this army were almost unsolvable, even if he hired Haihan ships to transport supplies by sea, it would be difficult to maintain a supply line of thousands of miles from Hue to the southern border. Hai Han's fleet was barely enough to maintain a militia of three or four thousand men, but the supplies needed by the North Vietnamese army, which was ten times that size, were already more than the fleet could operate.

In this case, Zheng Bai had no better solution, so he could only use the most primitive way - local supply during the march. The relatively simple and easy-to-understand way of saying it is to rush all the way. Those who are willing to give food can still save the lives of their families and a small amount of food, but as long as they are unwilling to cooperate. Almost all of them were looted, and those who dared to resist might even lose their lives, anyway, human lives were not worth much during the war, and they would be killed if they were killed by the rebels.

This directly led the area south of Hue into great chaos, and the North Vietnamese army swept almost like locusts everywhere they went. Although Zheng Bai's original intention was only to collect supplies. However, when such orders reach the grassroots level, it is difficult to carry them out as they are. And for the North Vietnamese army. The north and the south were separated for many years, and their families were fighting north of the river, and they did not have much pity and sympathy for the people in the South Vietnamese region, and there was not much psychological pressure to rob the property, and soon the operation of collecting supplies turned into a feast of looting.

On the other side of the sea, when the Haihan Executive Committee sent a special team to Shilu, Zheng Bai commanded his army to advance to the Quang Ngai area, 400 miles south of Hue. At this time, the items in the army were not reduced due to continuous consumption, but they had tens of thousands of catties of baggage.

In addition to the military rations that were constantly collected by various means along the way, more of them were all kinds of personal belongings looted by the soldiers. After the soldiers grabbed the money. There was no place to store it, let alone spend it on the march, and there was no feasible way to transport it back to the north, so they had to be stored together, and often all the belongings looted by a group of people were put together in several large boxes, and then taken with them on the march. Fortunately, I also grabbed a lot of mules and horses and other livestock along the way south, but I don't need to worry about grabbing too many things and can't transport them away.

Zheng Bai is not blind. It is not uncommon to find such a situation in the army, but under the objective form of today, if these soldiers are not given material incentives, it is indeed somewhat unreasonable. Zheng Bai had heard that all the Hai Han militia were rewarded for their merits after the war, and all the property seized during the war should be confiscated, but unfortunately there was no such rule in the North Vietnamese army. Even those officers who had been trained in the Haihan Army probably would not agree to confiscate their share of property.

The South Vietnamese regime had collapsed, so the army did not encounter the same resistance as Quang Tri City in the process of clearing the remnants of South Vietnam along the way, and the defenders often collapsed at the first touch, or surrendered directly to the city. The frequent and intensive skirmishes that Zheng Bai feared did not materialize. But this kind of marching method of robbing and killing along the way has also caused another evil, that is, a large number of bankrupt people have appeared in the places they passed. And their only choice is probably to flee their homes. As a result, there was the second wave of refugees in South Vietnam since 1627, and this time the location was no longer the north-south war zone near the Hung River, but moved to the coastal towns of Da Nang, Hoi An, Am Gi, Quang Ngai, and Anh Nh in the south.

Before the war, the Hai Han Executive Committee asked the North Vietnamese court for concession rights in Da Nang, Quy Nhon, Cam Ranh and Vung Tau, but at this time, except for Cam Ranh and Vung Tau further south, Da Nang and Quy Nhon were almost all white land, and the people abandoned their homes and fled under the plundering of the North Vietnamese army. And this situation undoubtedly adds more difficulty to the development plan that Haihan wants to implement here. After all, the development and construction of the port requires a large amount of labor, and the executive committee directly intends to recruit the main labor from the local area when planning, and only send management personnel from the base camp. However, as soon as the North Vietnamese army made such a fuss, I am afraid that the Executive Committee would have to reconsider the distribution of the sources of labor.

However, it is true that the Executive Committee has no better way to solve the current problems for the North Vietnamese, because with the launch of the Shirok project, the Executive Committee needs to concentrate more maritime capacity on the Victory Port-Changhua route, and it is impossible to send more sea ships to solve the problem of transporting supplies for the North Vietnamese army. The North Vietnamese Army made a mess in the local area, and the Executive Committee could only stare at it, after all, the original agreement only involved the right to use and own the local land, and did not say that the population of the surrounding area should be kept by Haihan.

The Executive Committee is also quite helpless about this situation. According to the development plan agreed by the executive committee members last year, it was expected that construction work would begin at the two sites in Sirok and South Vietnam at the same time, but now it seems that it will be difficult to do both. After much deliberation, the Executive Committee decided to take care of the Shiroku Iron Mine, which is closer to Shengli Port and more important for the future development of the Group. Although the construction time of the Sirok iron ore project may be much longer than the time required to develop the port of South Vietnam, the importance cannot be equal.

Regarding this decision, Yan Chujie expressed a viewpoint at the executive committee that was later widely discussed by the outside world: "If there is steel, there will be combat effectiveness, and if there is combat effectiveness, what else can we not grab? As long as our military strength is strong enough, it will not be impossible for us to take down the entire Indochina Peninsula in the future, not to mention these ports!"

Although the executive committee members do not fully agree with Yan Chujie's slightly extreme view, they have to admit that there is some truth in his statement. Armed with muskets and artillery, the Haihan militia is almost the strongest army in the Far East of the same size in this era, and the development of Shilu Iron Mine is bound to bring about a further improvement in military strength and even the comprehensive strength of the entire crossing group.

Therefore, after the members of the executive committee unified their understanding, the executive committee also made a decision to temporarily stop the port construction plan in South Vietnam and devote all resources to the development project of the Shiroku Iron Mine, so as to shorten the scheduled construction period and put the large project of the Shirok Iron Mine into actual operation as soon as possible. This decision led to the outbreak of a new wave of immigrants in 1629.