Pierre Joseph Georges Pigneau (2 November 1741[3] – 9 October 1799), commonly known as Pigneau de Béhaine (French: [piɲo də be.ɛn]), also Pierre Pigneaux, Bá Đa Lộc ("Pedro"[4] 百多祿), Bách Đa Lộc (伯多祿) and Bi Nhu ("Pigneau"[5] 悲柔), was a French Roman Catholic bishop best known for his role in assisting Nguyễn Ánh (later Emperor Gia Long) to establish the Nguyễn dynasty in Vietnam after the Tây Sơn rebellion.

After waiting for a few months in the Portuguese colony of Macau, Pigneau travelled on a Chinese ship to reach the small coastal town Hà Tiên in Cochinchina (Southern Vietnam) near the Cambodian border, set up by missionaries who had been displaced by the Burmese.

In 1769, the school was attacked by Chinese and Cambodian pirates, who massacred some of the students and burnt down the establishment...[10] Pigneau was forced to flee in December 1769 with the survivors to Pondicherry, then a French territory, after a long sea journey through Malacca.

[11] Pigneau de Behaine was appointed bishop in partibus infidelium of Adran in Syria,[13] and Apostolic Vicar of Cochinchina on 24 September 1771.

[14] After his ordination on 24 February 1774 in São Tomé near Madras,[15][16] he went to Macau to gather more staff before returning to resume his work in Ha Tien.

[17] In 1775-76, Pigneau attempted to convert the Stieng people, but the missionaries he sent suffered greatly, and either fell ill or returned.

He took refuge at Pigneau's seminary from September to October before both were forced to flee to the island of Pulo Panjang in the Gulf of Siam.

Pigneau in return attempted to obtain assistance from Manila, but the party of Dominicans he sent was captured by the Tây Sơn.

[27] The French administration in Pondicherry, led by the interim Governor Coutenceau des Algrains, successor of Bussy, seconded by Captain d'Entrecasteaux, was resolutely opposed to intervening in southern Vietnam, stating that it was not in the national interest.

In July 1786, Pigneau was allowed to travel back to France to ask the royal court directly for assistance.

[29] Arriving in February 1787 with the child prince Canh at the court of Louis XVI in Versailles,[30] Pigneau had difficulty in gathering support for a French expedition to install Nguyễn Ánh on the throne.

Eventually, he was able to seduce military figures with precise instructions as to the conditions of warfare in Indochina and materiel for the proposed campaign.

Prince Cảnh dazzled the Court and even played with the son of Louis XVI, Louis-Joseph, Dauphin of France, who was about the same age.

Four frigates, 1650 fully equipped French soldiers and 250 Indian sepoys were promised in return for Pulo Condore and harbour access at Tourane (Da Nang).

[39] A few days after the treaty was signed, the foreign minister sent instructions on 2 December 1787 to the Governor of Pondicherry Thomas Conway, which left the execution of the treaty to his own appreciation of the situation in Asia, stating that he was "free not to accomplish the expedition, or to delay it, according to his own opinion"[40] Louis XVI himself told Pigneau that Conway was appointed Governor of Pondicherry simply to remove him from Europe.

[42] The Dryade was ordered by Conway to continue to Poulo Condor to meet with Nguyễn Ánh and deliver him 1,000 muskets bought in France and Father Paul Nghi, a Cochinchinese missionary devotee of Mgr Pigneau.

Conway finally provided two ships to Pigneau, the Méduse, commanded by François Étienne de Rosily-Mesros,[43] and another frigate.

[43] Jean-Marie Dayot deserted the Pandour and was put in charge of supplies, transporting weapons and ammunitions on his ship the St. Esprit.

[49] In 1792, Dayot attacked the strategically important port of Qui Nhơn, opening the way to the Cochinchinese ships which then defeated the Tây Sơn fleet.

Pigneau de Behaine was the object of several funeral orations on behalf of emperor Gia Long and his son Prince Cảnh.

[52] In a funeral oration dated 8 December 1799, Gia Long praised Pigneau de Behaine's involvement in the defense of the country, as well as their personal friendship: Funeral oration of emperor Gia Long to Pigneau de Behaine (excerpt):"(...) Pondering without end the memory of his virtues, I wish to honour him again with my kindness, his Highness Bishop Pierre, former special envoy of the kingdom of France mandated to obtain a sea-based and land-based military assistance sent by decree by warships, him, this eminent personality of the Occident received as a guest of honour at Southern Court (...) Although he went to his own country to address a plea for help and rally the opinion in order to obtain military assistance, he was met with adverse conditions midway through his endeavour.

His ambition never materialised with the failure to convert Canh, who predeceased his father Nguyễn Ánh by twenty years in any case.

He had initially taught Canh to refuse to engage in ancestor worship, something that greatly shocked and angered Nguyễn Ánh.

He later changed his mind on the papal ban and proposed to consider ancestor worship as a civil ceremony, a simple manifestation of respect for the dead.