Nguyễn Ánh built a citadel in Diên Khánh and appointed Võ Tánh as the governor of the city. Shortly thereafter, Võ Tánh returned to Gia Định, where he was elevated to the position of Đại Tướng Quân ("Grand General") and was given the title Quận Công (lit., "Duke"). In 1797, Tánh assisted Nguyễn Ánh in launching a seaborne attack on Quảng Nam, where they quickly defeated the Tây Sơn garrison and occupied the province. In 1799, Nguyễn Ánh launched the third expedition to Quy Nhơn. The expedition was successful, and Nguyễn Ánh captured the Citadel of Quy Nhơn and renamed the fortress town Bình Định (lit., "Pacified"). Afterwards, Nguyễn Ánh appointed Võ Tánh as the new governor of the city and withdrew his main forces to Saigon. The Siege of Quy Nhơn In early 1800, two senior Tây Sơn generals, Tran Quang Dieu and Vu Van Dung, led a large force consisting of army and naval units toward Quy Nhơn with a view to recapturing it. The Tây Sơn swiftly occupied the territory surrounding the Citadel of Quy Nhơn, including the vital Thị Nại Port. Then, they set up a solid defensive system and besieged the citadel. Besides the military tactics, Tây Sơn commanders applied a psychological tactic that made the former Tây Sơn soldiers who were now serving in Nguyễn forces to defect and return to the Tây Sơn army. The tactic succeeded, forcing Võ Tánh to seal the citadel's door and wait for reinforcements. Although Nguyễn Ánh immediately led a force northwards to Quy Nhơn in order to relieve Võ Tánh's besieged forces, the Nguyễn reinforcements could not break the Tây Sơn encirclement and a long battle resulted. Acknowledging the poor situation, Nguyễn Ánh ordered Võ Tánh to abandon the citadel, but Võ Tánh rejected and suggested that he would pin the main Tây Sơn force down there so that Nguyễn Ánh could attack their Citadel of Phú Xuân. Nguyễn Ánh agreed and then he attacked and captured Phú Xuân, forcing Tây Sơn emperor Quang Toan to flee to northern Vietnam. This victory was a turning point of the war, from which the Tây Sơn became very weak and never posed any other significant threat to Nguyễn Ánh. The siege of Quy Nhơn continued for over a year to June 1801, when the citadel's food provisions were exhausted. Death After refusing to consider the thought of a surrender,