After defeating the Tay Son Dynasty and ascending to the throne, Emperor Gia Long collected copper throughout the country to cast the "Nine Holy Cannon" (Chinese characters:九位神仰), or nine cannon, as a symbol of the power of the Nguyen Dynasty. 

These nine cannons are considered Vietnam's largest and one of the most valuable bronze works of art. Nine Holy Cannons have never been used in battle, but only used in firing commands in the Capital when taking place court rituals such as Longevity ceremony, New Year, or Nam Giao Esplanade rituals but the role of these cannons is always considered both a god and a sacred object to protect Hue city.

In 2012, Nine Holy Cannons was recognized as a Vietnamese National Treasure under the Prime Minister's Decision No. 1426/QD-TTg dated December 01, 2012.

After defeating the Tay Son Dynasty, Emperor Gia Long ordered all confiscated bronze weapons to be cast into nine cannons to "make eternal memories" of his victory. Work began on January 31, 1803, and was completed by the end of January 1804.

In order to cast the Nine Holy Cannons, Emperor Gia Long personally sought the most elite workers, not only skilled but also ethical to trust with the work. The casting of cannons was under the supervision of Marshal Nguyen Van Khiem, Chief of Administration Hoang Van Can, Deputy Chief of Administration Ich Van Hieu, and Public Works Ministry Phan Tan Can. Mr. Phan Tan Can was recently promoted to the Assessor of Public Works Ministry, was careful with each drawing, applied modern techniques, and did not ignore the traditional elements of feng shui and numerology.

Once completed, the Nine Holy Cannons were placed directly to the left of the main gate of the Ngo Gate in Hue Citadel, and a team of soldiers was sent to guard. By 1917 in the reign of Khai Dinh emperor, the cannons were moved to the flag tower as today.

The nine cannons are divided into two groups: the "Four Seasons" group including 4 cannons of Spring - Summer - Autumn - East and the "Five Elements" group including 5 cannons of Metal - Wood - Water - Fire - Earth. Previously, the Nine Holy Cannons were placed in front of Ngo Gate - the main door of the Imperial Citadel, in two rows of cannon workshops; now they are located at The Nhon Gate (Ngan Gate) and Quang Duc Gate (Sap Gate) of Hue Citadel.

Name and rank of the cannon

Each cannon has a length of 5,1m with an inner diameter of 22,5cm; On the body, there are many exquisite decorative patterns and short texts about the history of the cannon. The cannon's knob has the name and rank of each cannon, as Xuan (Spring) is known as "the first of the Nine Holy Cannons"... There is an inscription on the carriage about how to make suppositories.

Painted in the journal “Bulletin des Amis du Vieux Hué” (Friends of Hue Ancient Capital) No. 2 Avril-Juin 1914. Translation by Thuan Hoa Publishing House. (Photo by Manhhai, Flickr, CC BY 2.0)

The nine guns were all very large in size and weight, with an average of 11.000kg each. Each gun is mounted on an elaborately carved wooden carriage. The two sides of the carriage have 4 wooden wheels bordered with iron for convenient movement. The cannon's body is engraved with text and decorative patterns.

In addition to the cannon's name, dating to the third year of Gia Long (1804), the cannon's body is also engraved with the weight of each gun by weight unit (the heaviest gun weighs 18,400 kg, the lightest gun weighs 17,200 kg). Symmetrically for each weight mark on each gun, there is also a short article stating the reason for casting the gun, and how to make ammunition. In 1816, Emperor Gia Long gave all nine cannons the title "Than Oai Vo Dich Thuong Tuong Quan", which means “The nine undefeated holy cannons”. This title and the content of the ordination are engraved on all 9 cannons.

In addition, there are patterns decorated with flowers and leaves and there are two large straps in the shape of two very sophisticated qiling. On the cannons are also engraved the names of the people who instruct the construction of these guns, including Marshal Nguyen Van Khiem, Captain Hoang Van Can, Captain Cai Van Hieu and Assessor of Public Works Ministry Phan Tien Can.
 

In addition to historical value, Nine Holy Cannons is also considered a beautiful sculpture, showing art - metallurgical techniques and casting at the peak of the Nguyen Dynasty. These are the largest cannons in Vietnam, one of the most valuable sets of bronze artworks of the nation. Over 200 years, the three cannons still exist almost intact, and present as an important part of the cultural heritage system of Thua Thien Hue province.