Ss Andrew Kim Taegon, Paul Chong Hasang and Companions (September 20) are being honoured by the Month of Martyrs in South Korea

Although few know about these historical events outside Korean Christian circles, up to 8,000 Catholics were martyred during persecutions in Korea in the 19th century in the last great period of oppression before the age of Communism and Islamism.

In May 1984, 103 martyrs were canonised and this month the Catholic Church in South Korea is holding a “month of martyrs” with the support of Pope Francis. The first conversions in the traditionally Confucian country began in the late 19th century, around the time when the first Christian books written in Chinese were imported in 1777. By the time a Chinese priest arrived at the end of the century he found about 4,000 Catholics – none of whom had ever seen a priest. The faith had been maintained by aristocratic laymen, the only people who could read at the time, who had sent a delegation on foot 750 miles to Peking asking for a priest. They got two, but they soon returned and it was another 40 years before the arrival of Fr Mauban, Paul Chong Hasang, Augustine Yu Chin-gil and Charles Cho Shin-chol. Missionaries faced extreme penalties if caught and travelled only at night.

The first Korean priest, Fr Andrew Kim Taegon, was executed in 1846 aged only 25. Other martyrs included Paul Chong Hasang and his father Augustine, Peter Yu tae-chol, John Baptist Yi and Thomas Son Chason.

What especially irked traditional Koreans was that this new faith seemed to undermine class distinctions, encouraging the poor to mingle with their betters. By the time the persecutions had ended in 1866, there were only 20,000 Catholics left in the country, while the vast majority of martyrs were lay people

Seventy-nine of the martyrs of 1839 were beatified in 1925, while another 24 were beatified in 1968. John Paul II canonised all 103 martyrs in Seoul in 1984. The Holy Father said that day: “The Korean Church is unique because it was founded entirely by lay people. This fledgling Church, so young and yet so strong in faith, withstood wave after wave of fierce persecution. Even today their undying spirit sustains the Christians in the Church of silence in the north of this tragically divided land.”

Korea is now thought to have the fourth largest number of saints on earth. In 2004 the Archdiocese of Seoul opened an investigation into the Cause for beatification of the Servant of God Paul Yun Ji-Chung and his 123 companions, who in 1791 were tortured and killed in odium fidei – in hatred of the faith.

Today the sacrifice of the faithful in Korea is marked by the Korean Martyrs Museum-Shrine in Seoul, which contains rooms for liturgical celebration and prayer. It was was built in 1967 on the site in the city where many of the Korean martyrs died from 1866 to 1873.