Andrew Dũng-Lạc was born at Trần An Dũng in 1795. He came from a poor, non-Christian family and was taught by a Christian lay catechist. He worked in the missions with the priests of the Foreign Mission Society of Paris.
He was imprisoned and repeatedly tortured during the persecutions of Minh-Meng, the emperor of Vietnam between 1820 and 1840 who was famed for his persecutions of the Christians.
He became a Vietnamese Roman Catholic priest on 15 March 1823.
Christianity came to Vietnam through the Portuguese. Jesuits opened the first permanent mission at Da Nang in 1615. They ministered to Japanese Catholics who had been driven from Japan.
Foreign missionaries were banned by the king in one of the kingdoms in Vietnam. The king also tried making all Vietnamese deny their faith by trampling on a crucifix.
Like the priest-holes in Ireland during English persecution, many hiding places were offered in homes of the faithful.
Serious persecutions were launched three times in the 19th century. During the six decades after 1820, between 100,000 and 300,000 Catholics were killed or subjected to great hardship.
Foreign missionaries martyred in the first wave included priests of the Paris Mission Society, and Spanish Dominican priests and tertiaries.
Another persecution broke out in 1847 when the emperor suspected foreign missionaries and Vietnamese Christians of sympathizing with a rebellion led by of one of his sons.
During persecution, Andrew Dũng changed his name to Lạc to avoid capture, and thus he is memorialised as Andrew Dũng-Lạc. He was arrested and beheaded on December 21 with Peter Thi.
The last of the martyrs were 17 laypersons, one of them a 9-year-old, executed in 1862. That year a treaty with France guaranteed religious freedom to Catholics, but it did not stop all persecution.
Andrew Dung-Lac was among the 117 people martyred in Vietnam between 1820 and 1862. These people were beatified on four different occasions between 1900 and 1951. All were canonized by Pope John Paul II.