Unlike traditional Vietnamese warfare in northern Vietnam that was conducted during the winter dry season when north winds blew from the continent into the sea, Nguyen Phuc Anh’s campaigns were organized to catch the south winds that blew from the sea from late spring into autumn. His basic strategy was to move north by sea with the winds, landing troops and supplies to support the advance of land armies. When the winds changed he would return to Saigon with his fleet and leave land forces in defensive positions to hold off the enemy until the following year when the south winds returned. Nguyen Phuc Anh’s first experiment with this type of warfare was in 1790 when he ordered an advance up the coast into Binh Thuan. This was a dry region that produced little rice. There were no important harbors. The Cham popula- tion was concentrated here and had provided strong support to Nguyen Nhac. After initial success in marching north through Binh Thuan, Nguyen Phuc Anh’s generals floundered in confusion when Nguyen Nhac counterattacked. By the end of the year, Nguyen Phuc Anh had withdrawn his forces back to their starting point at Ba Ria. During the following year, Nguyen Phuc Anh concentrated upon rebuilding the morale of his officers after the dismaying Binh Thuan campaign. He also strengthened his military forces, dealt with a drought, spread propaganda in the north, and nurtured his alliance with Siam. This was the first year that the conscription procedure among Vietnamese was made annual. New army units were organized with volunteers from the Chinese communities. Military colonies (don dien) were established among the Chinese at Long Xuyen, among the Khmers at Can Tho, and among the Vietnamese at Ba Ria. Lumber was brought from Cambodia to the My Tho shipyard and some one hundred ships were built. The Saigon shipyard was building ships that could carry twenty-six to thirty-six cannon and over three hundred men. Rice was purchased in Siam to alleviate near famine conditions caused by drought, and measures were taken to keep local rice from being hoarded or made into wine. People continued to arrive from the north, and they had to be examined to sort out loyal people from spies. Meanwhile spies were sent into the north to inspect conditions there and to spread songs of nostalgia for the Nguyen Phuc and of anticipation for the south wind that would bring the Nguyen Phuc back to power. Literary examinations were held to test knowledge of history and the ability to think about current events. Those who achieved the best grades were assigned to teach in government schools. Others received tax and conscription exemptions and were assigned to continue their studies. Shrines were built for the souls of those who had perished in battle. The Laotian king had captured some of Nguyen Hue’s soldiers, banners, and drums during Nguyen Hue’s expedition into Laos of this year. He sent these to his Siamese overlord, who forwarded them to Nguyen Phuc Anh. Nguyen Phuc Anh sent an envoy to Chakri at Bangkok conveying his appreciation. The envoy was also instructed to explain to Chakri that, although there were bound to be tensions and unfortunate events along the Khmer–Viet border, Nguyen Phuc Anh regarded Cambodia as a Siamese vassal and would refer all matters regarding Cambodia to him. The two kings throughout their reigns maintained a plausible appearance of trust. In 1792, Nguyen Phuc Anh waited until his spies reported a large enemy fleet at Qui Nhon, Nguyen Nhac’s harbor. He sent his fleet, which captured the enemy ships and briefly occupied Qui Nhon before returning to Saigon. During this operation, his land soldiers advanced as far as Phan Rang before turning back to Ba Ria when the winds changed. Cham leaders in Binh Thuan pledged loyalty to Nguyen Phuc Anh, and a good harvest brought an end to the famine laws. News from the north was also encouraging. After Nguyen Hue’s death, tension between Nguyen Nhac and the leaders at Phu Xuan had prevented Nguyen Nhac from attending his brother’s funerary rites. In 1791 and 1792, the relationship between Nguyen Phuc Anh and Pierre Pigneau was nearly broken over the issue of Pigneau’s role as teacher and mentor of Prince Canh. Nguyen Phuc Anh was dismayed by his son’s fidelity to his Christian education in rejecting certain features of local culture, in particular the veneration of his ancestors. He consequently relieved Pigneau of his responsi- bilities as Prince Canh’s teacher. He was also impatient with Pigneau’s incessant urgings to attack the Tay Son before he considered the time to be propitious. At one point, Pigneau threatened to leave. By 1793, however, after much discussion between the two men, mutual accommodations opened the way for reconcili- ation. Pigneau was reinstated as Prince Canh’s mentor, Prince Canh emerged from adolescence and became more tolerant of local practices, and Nguyen Phuc Anh was ready to move north. Nguyen Phuc Anh’s south wind campaign of 1793 was a success that greatly advanced his battlefield position. In preparation for it, early in the year he issued an edict calling on the people to abandon lazy habits and work hard to serve the country. He also issued a call for special efforts against thieves and bandits. He then began to mobilize his soldiers, including an army of Khmers and an army recruited from upland peoples. Families of soldiers, including the Khmers, received tax exemptions. Qing, Siamese, and French were serving in the fleet along with the Vietnamese. In the fifth lunar month, with a strong south wind, Nguyen Phuc Anh took his fleet up the coast and seized Nha Trang, where he was joined by his land armies. His land and sea forces then advanced through Phu Yen and, after heavy fighting, captured strategic positions around Cha Ban, Nguyen Nhac’s capital, and the seaport of Qui Nhon. While his armies were occupied with taking the surrender of enemy soldiers and with collecting weapons at Cha Ban and Qui Nhon, Nguyen Phuc Anh took his fleet north to Quang Ngai where he rallied supporters from among the local population and fought several battles against armies from Phu Xuan seeking to come to Nguyen Nhac’s assistance. As the winds began to change, Nguyen Phuc Anh withdrew his forces to Phu Yen. He then mobilized some four thousand men from Binh Thuan to build a fortress at Dien Khanh, under the supervision of Olivier de Puymanel. Dien Khanh, about fifteen kilometers west of Nha Trang, is the modern capital of Khanh Hoa Province. It is strategically located to guard the way south out of the Nha Trang region. A system of post houses and storehouses in Binh Thuan linking Gia Dinh with Dien Khanh was established. Nguyen Phuc Anh was determined to defend Dien Khanh at all costs. Leadership among Nguyen Phuc Anh’s enemies weakened as a result of the 1793 battles. Nguyen Nhac died, reportedly in a fit of chagrin because his generals did not follow his commands during the battles around his capital. His son and heir, Nguyen Bao, immediately began to quarrel with the leaders at Phu Xuan. But the building of the Dien Khanh fortress gave these men a target against which they could unite, at least temporarily. The fighting of the next two years was basically an unsuccessful effort by the Phu Xuan generals to seize Dien Khanh. Nguyen Phuc Anh had succeeded in shifting the focus of battle to a place of his choosing. During the 1793–1794 dry season, virtually all of Nguyen Phuc Anh’s activ- ities were oriented toward strengthening Dien Khanh. Ships and weapons were being produced as fast as possible. Militia units were organized in Binh Thuan and in the region of Dien Khanh. Men from Quang Ngai who had rallied during the 1793 fighting were organized into an army. Dien Khanh was reinforced not only with Vietnamese soldiers but also with units of Khmers, Siamese, and Malays. Cham soldiers at Dien Khanh were released to serve in their home province of Binh Thuan as supply troops. A Cham leader who supported the Tay Son was captured and killed. Vietnamese settlers were assigned to work the fields that had been abandoned by Chams in Binh Thuan. Amidst all of this, Nguyen Phuc Anh arranged to sell rice to Siam to alleviate a famine there. When, in spring 1794, a large Tay Son army marched into Phu Yen, forcing his men to retreat, Nguyen Phuc Anh hastened rice and men to Dien Khanh. Shortly after, the Tay Son advanced to attack Dien Khanh. By this time the south wind allowed Nguyen Phuc Anh to set sail with his fleet. News of this led to the Tay Son withdrawing back to Phu Yen. Nguyen Phuc Anh advanced to Phu Yen, fought many battles there, and also sent seaborne forces to disrupt Tay Son communications in Quang Ngai. Reinforcements were summoned to the Phu Yen battlefront as he visited Dien Khanh and ordered repairs to the fortress. The Siamese soldiers at Dien Khanh were allowed to return to their country. Officials in Saigon were instructed to issue them their pay as they passed through. Before returning to Saigon, Nguyen Phuc Anh endeavored to resolve problems caused by sending Vietnamese to cultivate former Cham lands in Binh Thuan. He ordered Vietnamese officials to consult with Cham officials to adjudicate bound- ary disputes fairly so that the two peoples could live together in peace. Shortly after the winds changed to the north in late 1794, the Tay Son returned to the offensive. As they fought their way south through Phu Yen and to the walls of Dien Khanh, Nguyen Phuc Anh rushed supplies and reinforcements to Vo Tanh, the commander at Dien Khanh. By the end of the year, after heavy fighting, the Tay Son armies had Dien Khanh under siege and were advancing into Binh Thuan. Within a few weeks, by early 1795, the Tay Son had pushed all the way to Ba Ria. An army of 1,500 Khmers was organized in Tra Vinh and, along with other Gia Dinh militia and reserve units, was ordered forward. The Tay Son forces were pushed back. Meanwhile, Nguyen Phuc Anh was with his fleet, filled with supplies and troops, waiting for the winds to change. When they did, he sailed to Nha Trang to disembark an army to relieve Dien Khanh, then continued to Phu Yen to disembark another army to block the Tay Son from escaping back north. During the next four months, fighting raged from Binh Thuan to Phu Yen. Defeated in Binh Thuan, Tay Son forces withdrew and joined the armies besieging Dien Khanh. At the same time, an army of uplanders helped Nguyen Phuc Anh to obtain an important victory in Phu Yen. Meanwhile, in Phu Xuan, murderous feuds broke into the open. A general named Vo Van Dung killed the regent, Bui Dac Tuyen. The general besieging Dien Khanh, Tran Quang Dieu, was a supporter of Bui Dac Tuyen, so Vo Van Dung sent agents to kill him. Before this could come to pass, the siege of Dien Khanh was broken when a Tay Son deserter revealed a mountain path that allowed a unit of Saigon soldiers to pry open the Tay Son position. The Tay Son armies fled north as their generals raced back to Phu Xuan to join the struggle for power. Eventually, Phu Xuan leadership was reorganized as a coalition of four powerful generals, each of whom desired supremacy. Two of these generals were Vo Van Dung and Tran Quang Dieu. Nguyen Toan, the young king, was powerless. For three years, the war had centered on Dien Khanh, a fortress built at a place chosen by Nguyen Phuc Anh as his first step up the coast from Saigon. The failure of his enemies to take Dien Khanh and their lack of unity made it possible for him to advance the focus of warfare further north into Binh Dinh.