Born on 7 February 1884, Achille Liénart, while a seminarian, was sympathetic to Marc Sangnier's Sillon movement but when the Sillon became more "political", he turned towards the ACJF movement.
He was ordained in 1907 and became a seminary professor in 1910.
During World War I, he was a military chaplain, who was awarded the Croix de Guerre with six citations as well as the Legion of Honour for his service in the front lines.
After the war, he became involved in the early ecumenical movement and eventually became president of the Judeo-Christian Friendship Association.
From the 1920s, he was was involved in social issues.
As soon as the YCW (JOC) was founded in Lille, he became chaplain to one of the first teams.
In 1928, he was named bishop of Lille by Pope Pius XI, who made him a cardinal two years later in recognition for his struggles alongside the workers. As a result he became known as the "red bishop".
From the 1930s, he supported the development of the worker priest movement, which also emerged from the JOC/YCW.
At Vatican II, it was Cardinal Liénart who made the epoch-making intervention at the first working session of the Council on 13 October 1962 which revolutionised Vatican II.
He retired in 1968 and died in 1973.
Testimonies on Cardijn and the JOC/YCW by Cardinal Liénart