Saint Jean Charles Cornay was born on February 28, 1809 in the city of Loudun, in the Vienne region of France. He was the son of a wealthy and religious family. Cornay was sent to the minor seminary in Montmorillon, Vienne, in the Nouvelle-Aquitaine region of France. He later studied at the Seminary of the Paris Foreign Missions Society (MEP).
When Cornay was ordained a deacon, the church superiors sent him to do missionary work in Sichuan province, China. However, the Sichuan authorities strictly controlled entry and did not allow missionaries. Therefore, Cornay's superiors asked him to go to Dai Nam (Vietnam), from where it would be easier to enter Sichuan. Cornay arrived in Dai Nam with Bishop Liêu and two other missionary priests. However, due to an incident, he could not proceed to Sichuan. Cornay later met Bishop Du and was ordained a priest. The parishioners called him by the Vietnamese name Co Tan.
Father Jean Cornay was a gentle, sincere, humble man who offended no one, so he was respected by all. In Bau No village, No Luc, there was a bandit named Duc who had been imprisoned in Son Tay for previous crimes. After being released, Duc sought revenge, so he buried a gun near the parish house and accused the Western priest in the village of possessing weapons and frequently meeting with the French enemy.
The royal court sent 1,500 soldiers to arrest Father Cornay. He was shackled, and 40 witnesses were also tied up. At the court, three high officials interrogated Cornay about when he came to Dai Nam, how he entered, where he stayed, his areas of activity, etc. When asked "Why did you come to conquer Dai Nam?", Cornay replied that he only came to preach.
After the trial, King Minh Mang sentenced Cornay as a French rebel leader, despite his denial of any connection to the enemy. Upon learning of his death sentence, Cornay wrote to Father Phan expressing joy at reuniting with God, and wishing to confess, receive absolution and final rites before execution.
On September 20, 1837, Father Jean Charles Cornay was brought to the Nam Mau execution grounds. The wooden plaque stated his crime as "French rebel leader, head of Catholicism". After beheading, his body was displayed for 3 days then thrown into the river by royal order. Later, his remains were found and buried by the Congregation of the Blessed Cross.
Father Jean Charles Cornay was beatified on May 27, 1900 and canonized on June 19, 1988.