The citadel was involved in two wars prior to its destruction, first when it was captured by Lê Văn Khôi in 1833 and used in a revolt against Emperor Minh Mạng, then recaptured in 1835.

[1] Following the capture of the citadel, Minh Mạng ordered its razing and replacement with a smaller square stone-built structure, that was more vulnerable to attacks.

On February 17, 1859, the citadel was captured during the French invasion after less than a day of battle and significant amounts of military supplies were seized.

Realising that they did not have the capacity to hold the fort against Vietnamese attempts to recapture it, the French razed it with explosives, before withdrawing their troops.

[5][6][7] Nguyễn Ánh fled to Hà Tiên in the far south of the country, where he met Pigneau de Behaine,[3][8][9] a French priest who became his adviser and played a large part in his rise to power.

[3] The Tây Sơn regularly raided the rice growing areas of the south during the harvesting season, confiscating the Nguyễns' supply of food.

[12] His grip on the south was enhanced by a group of Frenchmen and equipment that Pigneau had recruited, although the magnitude of the aid has been the source of dispute.

[6][7][12][13][14][15][16][17] Having seen Saigon slip from his hands on many occasions in the previous decade,[3] Nguyễn Ánh was keen to strengthen his hold on the key southern city, turning it into his capital,[18] and the base for his preparations for his planned conquest of the Tây Sơn and Vietnam.

[18] The French officers recruited by Pigneau were used to train Nguyễn Ánh's armed forces and introduce their technological expertise to the war effort.

[12][15][19] One of Nguyễn Ánh's first actions was to ask the French officers to design and oversee the construction of a modern European-style citadel in Saigon.

[18] It was described as being of a Chinese style, designed in the octagonal form of a lotus flower, with eight gates[18] in the Đại Nam nhất thống chí, the official records of the Nguyễn dynasty.

Two French maps of the city, drawn by de Puymanel and Jean-Marie Dayot—another senior officer[12]—in 1799 and 1815 respectively, show a square-shaped design, with four main towers at the corners, and six outer half-towers, centered at 10°46′58″N 106°41′53″E / 10.78278°N 106.69806°E / 10.78278; 106.69806.

[20] The design suggested by the French maps is corroborated by the accounts of British and American visitors who travelled to Saigon seeking trade deals for their respective countries in the 1820s.

British trade envoy John Crawfurd wrote that "the citadel of Saigon...is, in form, a parallelogram...I conjecture, from appearance, that the longest side of the square may be about three-quarters of a mile in length".

[20][21] George Finlayson, a naturalist and surgeon who travelled to southern Vietnam as a member of a trade delegation from the British East India Company, described the fortress as being "of square form, and each side is about half a mile in extent".

The palace itself was estimated by White to have covered an area of 3.25 hectares (8.0 acres), standing at the centre of the citadel on a green, enclosed by paling.

[25] A cemetery stood at the western end of the citadel, with prominent mandarins being interred there, while the arsenal was located in the northeast section in six large buildings.

[27] Following the construction of the citadel, the Tây Sơn never again attempted to recapture the city—the building gave Nguyễn Ánh a further psychological advantage over his opponents.

[28] The citadel helped to secure the southern region, which allowed Nguyễn Ánh to implement domestic programs to strengthen himself economically in preparation to fight the Tây Sơn.

[15][32][33] The citadel was not used during the rule of Gia Long and the only military action occurred after his son had ascended the throne as Minh Mạng.

[22] Years of tension between the monarch and General Lê Văn Duyệt, the governor of southern Vietnam,[34] came to a head after the death of the latter in 1831.

The new mandarins carried out a detailed inquiry into Duyệt's rule and claimed that widespread corruption and abuse of power took place.

[35] Bạch Xuân Nguyên, the head of the inquiry, called for Duyet's posthumous prosecution, which resulted in 100 lashes being applied to his grave.

[39] This action prompted the Duyệt's officials—fearful of their positions and security under the central system—to launch a revolt under the leadership of his adopted son Lê Văn Khôi.

On the same evening, Khoi's men assassinated Nguyen Van Que, the newly appointed Governor-General who was overseeing the integration of the south into the central administration.

[39] Khoi then convinced a French priest named Joseph Marchand to come and stay within the citadel, hoping that his presence would win over support from the local Catholics.

[39] Vietnamese priests went on to lead Catholic armies in fighting off imperial forces as well providing messengers to communicate with the world outside their besieged citadel.

[40] Although Khôi himself died during the siege in November 1834,[40] the other rebels defending the citadel of Saigon held out against imperial troops until September 1835.

Charles Rigault de Genouilly led 500 French troops in hand-to-hand combat for seven hours, having used explosives to breach the citadel.

These militia engaged in ambushing French patrols near the citadel, as well as evacuating local inhabitants, in order to create an open space close to their target.