After the Trinh army withdrew north in early 1634, there was a change of leadership in the south. Dao Duy Tu died later that year, and Nguyen Phuc Nguyen died a year after that. His son, Nguyen Phuc Lan, was 35 years old when he came to power in 1635. He was assisted by an uncle, Nguyen Khe, by a cousin, Nguyen Tuyen, and by his full brother, Nguyen An, all capable and loyal men. When Nguyen Anh, the royal brother whose schemes had failed to benefit from the Trinh invasion of 1633, openly rebelled, he was captured and killed after a battle that left many dead. Nguyen Phuc Lan moved the site of his government a bit further south, into what today is the northern fringe of the modern city of Hue. Nguyen Phuc Lan viewed the northern border with relative complacency, and events in 1640 tended to confirm this attitude. Nguyen Khac Liet, the Trinh commander in charge of Northern Bo Chinh, on the northern bank of the Gianh River, which served as the border between the two realms, was apparently overly excited by his position on the border and, some years before, had begun to play a traitor’s game by secretly pledging allegiance to Nguyen Phuc Lan. However, his arrogant behavior subsequently lost him the trust of both Trinh Trang and Nguyen Phuc Lan. When his activities began to stir unrest in Southern Bo Chinh, on the southern bank of the Gianh River, Nguyen Phuc Lan consulted with his generals. Following the advice of Nguyen Huu Dat, a letter was sent to Trinh Trang reporting Nguyen Khac Liet’s treachery and pretending that his offer to serve Nguyen Phuc Lan had been refused. The idea was that if Trinh Trang sent a force to arrest Nguyen Khac Liet, the Nguyen would call on his previous pledge of allegiance to facilitate the movement of Nguyen forces across the river. Whichever way he turned, Nguyen Khac Liet would be easily eliminated, either by the southerners or by the northerners. When a northern army approached to arrest Nguyen Khac Liet, the southern- ers attacked across the river and sent him fleeing into its arms. He was taken north and starved to death in prison. Meanwhile, the southerners gained control of Northern Bo Chinh. When Trinh Trang requested the return of this territory, Nguyen Phuc Lan agreed, having succeeded in establishing a new measure of peace along the riverine border. In the wake of these events, a certain noble at Nguyen Phuc Lan’s court cited the ancient sages and Trinh perfidy to advocate a more aggressive policy toward the north. Nguyen Phuc Lan responded by calling the man a fawner and dismissed him. Yet, two years later, when he decided that he wanted to attack the north, he found that his “boat soldiers” were not in a state of readiness, so he instituted a program of intense training for them. As it turned out, Trinh Trang was a step ahead of him. In the dry season of 1643–1644, a large Trinh expedition marched and sailed south. Trinh Tac and Pham Cong Tru led the van. Trinh Trang and the king came with the main body of troops. The northern army brushed aside southern forces in Southern Bo Chinh and advanced to the wall at Dong Hoi, but northern efforts to break through the wall were repulsed. When the hot summer weather arrived, an epidemic ravaged the northern camp and the Trinh army withdrew. The Dutch also participated in this campaign, having arranged with Trinh Trang to join in combined action against the south. The hostile Dutch attitude toward the south had hardened after two of their ships en route from Formosa to Batavia were shipwrecked on the southern Vietnamese coast in late 1641. All salvageable merchandise was confiscated and the eighty-two survivors were detained and placed under the supervision of the Japanese community in Hoi An. Early the next year, the commander of a Dutch ship sailing to Batavia with a Trinh envoy was persuaded by the envoy to stop at Da Nang Bay to seize hostages. He seized over 100 people. Then, hearing about the Dutchmen held at Hoi An, he tried to negotiate an exchange with a local official. Thinking he had an agreement, he released the people he had seized, but he kept the Nguyen official and the official’s Japanese interpreter pending release of the Dutchmen. The Vietnamese authorities then refused to release the Dutchmen until not only the official and the interpreter were released but also the northern envoy was handed over. Worried about rumors of approaching Vietnamese war galleys, the Dutch weighed anchor and sailed off to Batavia. Apparently seeking to appear conciliatory, the Nguyen Phuc authorities allowed fifty of the Dutch hostages to board an unarmed ship and sail for Batavia. However, the Portuguese attacked the boat at sea and all the Dutchmen perished except for fourteen who washed up on the Cham coast where they were enslaved. One of them escaped to Cambodia from where he made his way to Batavia. The friendly gesture of releasing the fifty men was lost on the Dutch authorities at Batavia, who were determined on revenge for what they considered to be southern Vietnamese hostility toward them. Thinking that the Trinh were planning to campaign against the southerners in 1642, in that year the Dutch sent five ships with over 200 sailors and soldiers to raid the coast and seize hostages before joining the northern army at the border. In Quang Ngai, they burned down several hundred houses, as well as a rice granary, and seized dozens of captives. At Cu Lao Cham, an island off the coast near Hoi An, a Dutch foray was repulsed with heavy losses. After this, Dutch demands for the release of their men were ignored and the Dutch killed some of their hostages before sailing north. Discovering that there was no Trinh campaign that year, the Dutch met with northern authorities to plan for a campaign the following year. In early 1643, five Dutch ships arrived in northern Vietnam from Formosa to coordinate with the Trinh campaign, but the Trinh forces were not scheduled to depart for the south until later in the year. The Dutch commander would not wait, but agreed to leave one ship to go with the Trinh expedition, and then departed for Batavia. Contrary winds forced back two of the Dutch ships, so three Dutch ships were available to accompany the Trinh campaign. Learning of this, the authorities at Batavia ordered three ships under the command of Pieter Baeck to sail from the Straits of Malacca to the Gianh River border on a schedule to arrive at the time of the expected campaign. Meanwhile, the Trinh army was already encamped at the border. The three Dutch ships that had joined the Trinh earlier in the year were in the vicinity but inactive. Pieter Baeck was instructed to place these ships under his authority and to coordinate with the Trinh battle plans. Southerners at coastal watchtowers sighted Pieter Baeck’s ships as they sailed north. Nguyen Phuc Lan’s 25-year-old son and heir, Nguyen Phuc Tan, went in pursuit of them with sixty war galleys and engaged them in battle. The sounds of the battle from across the water were audible in the Trinh camp. The Dutch flagship caught fire and blew up when its powder magazine ignited. The other two Dutch ships were heavily damaged and escaped with difficulty. Pieter Baeck and one of the other Dutch captains were among those killed. The Dutch briefly attempted to blockade Hoi An in 1644. Various efforts were made to mediate the release of the fourteen Dutchmen remaining in custody there, including an initiative by Alexandre de Rhodes, who happened to be in Hoi An at that time. However, the Dutch authorities had grown weary of their frustrations along the southern Vietnamese coast and gave no more attention to the matter until a brief effort at making peace was made with Nguyen Phuc Lan’s successor in 1651. The Dutch embarrassment from their defeat in the 1643 battle with the southern Vietnamese was contemporaneous with similar misadventures in Cambodia. Their consequent loss of prestige affected their trading operations in northern Vietnam, where they suddenly began to suffer in unprecedented ways from the depredations of greedy eunuchs and officials and to find that competition from Chinese mer- chants began to squeeze their portion of the silk market. From then on, the Dutch stayed clear of any further military alliance with the Trinh. The Trinh followed up their disappointing southern adventure of 1643–1644 with an unsuccessful attack on Cao Bang led by Trinh Tac. Trinh Trang, then 68 years old, was beginning to lose his health and, in 1645, officially delegated decision-making powers to Trinh Tac. Trinh Tac then established his own court to govern the country. Two of his brothers led a rebellion against him in that year resulting in a battle that raged through the streets of Dong Kinh and left, according to Dutch estimates, some 4,000 people dead. Trinh Tac’s rivals were captured and killed. Pham Cong Tru emerged as Trinh Tac’s chief advisor on non-military matters, and his Confucian education was almost immediately apparent in edicts exhorting officials to be honest and not to oppress the people with unlawful extortions. Another edict forbad anonymous letters that bewitched and confused the people, suggesting that treason was finding many forms of expression. The next few years were relatively uneventful as Trinh Tac prepared for another propitious time to send his soldiers south. In the south, the most salient piece of surviving information from this time is that in 1646 it was decreed that a new literary examination was to be held every nine years. The exam was for three days and consisted of three parts: (1) writing a type of poetic prose written in alternating four-six syllable lines; (2) writing the phu mode of rhythmic prose; and (3) writing prose essays on the classical books. At the same time, a system of ranks and appointments for graduates of this exam was put in place. In 1647, thirty-one men were selected as a result of the first such exam. The widow of Nguyen Phuc Lan’s elder brother, who had died in 1631, was known as Lady Tong. She was both beautiful and a clever conversationalist. In 1639 she had gained entry to Nguyen Phuc Lan’s palace over the objections of some of his advisors who worried about her father who had turned coat and fled to the north. Nguyen Phuc Lan’s younger brother, Prince Trung, became involved with her and fell into a conspiracy facilitated by her father to assist a northern invasion. The conspiracy was uncovered and Prince Trung died in prison. But the Trinh invasion of 1648 that arose in the context of this intrigue was the most serious test of southern defenses yet. The Trinh broke through the first wall and took the fortress of Dinh Muoi, which was the center of the southern defense system. The northerners were breaking through the second wall when their offensive stalled. Truong Phuc Phan was in command of the section of the wall that was crumbling before the northern advance. His father had come south with Nguyen Hoang and by this time he was an old man. His son Truong Phuc Hung stood beside him as he sat calmly atop the wall under his parasol of authority directing the southern defense. His confident demeanor reportedly appeared to his troops as if he were a deity, which inspired them to greater effort. A female spy provided important information that helped to time a southern counterattack. Nguyen Huu Dat, in the midst of the battle, raised his eyes to the sky and observed in the clouds signs of southern victory. Nguyen Huu Tien shifted the fortunes of battle with a nighttime attack of one hundred bull elephants. Nguyen Phuc Lan was dying and had given command of the armies to his heir Nguyen Phuc Tan. The southern defenses were stretched to their limit, but they held, and the northern armies were pushed back and forced to return north. Nguyen Phuc Lan died within a day of reviewing his victorious troops. Nguyen Phuc Tan was 28 years old when he assumed supreme authority after this grueling battle. His leadership during the next four decades continued the tradition of astute rule that had been established by his predecessors. Neither he nor his opponent in the north, Trinh Tac, was committed to a war begun by their fathers. Both eventually understood that there was no benefit from warring upon each other, but the forces producing the war were too strong to be halted immediately. In both the north and the south were many men who harbored dreams of conquest. After the fighting of 1648, the nature of the war shifted. Until then, it was a war of northern campaigns against the south. In the 1650s, as Trinh Trang slowly sank toward the grave and as challenges to Trinh Tac’s authority continued to stir up from within the Trinh family, the south invaded the north, moving the war into a new phase during which fundamental changes occurred in both the north and the south that eventually led to an end of hostilities. During the 1620s, 1630s, and 1640s, the north had attacked the south as often and with as much vigor as it was capable of doing. During the same time, the southerners had evaluated their relative inferiority in men and resources and had prepared defenses that were equal to the northern challenge. Despite the drama of war, fundamental changes in society, economy, and culture were taking place in both the north and the south that focused the north inward and the south outward. The sheer size of the population in the Red River plain kept Trinh attention upon the task of socializing large numbers of people to respond to authority. Meanwhile, the southerners were awakening to the beckoning possi- bilities of the Mekong frontier.