Aiding others was risky. Some of the prisoners were shot for dropping out of line, while others were executed for aiding those who had become immobilized. Nonetheless, the bishop would help others. At one point he gave his entire blanket to a Methodist missionary who was suffering worse than he.
During a four-month-long forced march, suffering from bad weather and a lack of food and shelter, he began to succumb to pneumonia at Chunggan-up, not far from the Yalu River on the border with China.
He knew he was dying.
"After the privilege of my priesthood, I regard this privilege of having suffered for Christ with all of you as the greatest of my life," he told his companions.
He received absolution from his secretary, Father William Booth, the bishop's biography at the Maryknoll Mission Archives website says.
He died Nov. 25, 1950. News of his death took two years to reach the world, when U.N. prison camp inspectors found survivors of the march.
Bishop Byrne was buried by Msgr. Thomas Quinlan, an Irish-born Columban Father who placed his own cassock on the bishop. The monsignor was later named Bishop of Chunchon, South Korea.
Now, a special commission of South Korean bishops has begun a process that could make Bishop Byrne a candidate for beatification. The bishops have grouped him with Bishop Francis Borgia Hong Yong-ho of Pyongyang and 80 companions, who were killed in persecutions from 1901 to the mid-20th century.
Fr. Finch said the launch of the beatification process for Bishop Byrne was "a tremendous honor" and showed he was an example for the Maryknoll Society to follow.
"He answered the call to mission, from the very beginning, and stayed with it, and gave his life to that," he said. "That's what we want to do, one way or another, whether it's through a lifetime, or in a moment in which supreme sacrifices are asked for."
"We're inspired," the Maryknoll superior general said. "We're inspired by him, and we're inspired by a number of other Maryknollers who have given their lives over the years in Asia, in Latin America and in Africa."
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Other victims of the Korean conflict include Maryknoll Sisters like Sister Agneta Chang, who was kidnapped by the communist military in late 1950 and is believed to have been martyred.
"I believe they never found her body," Fr. Finch said.
While the context of the conflict was very difficult, it led to "tremendous Church growth" in South Korea after the war from people who were dedicated to the Church.
"Korea is one of the tremendous success stories of Asia: a Church that started out with 20-25,000 of people of the faith at the start of the last century and ended up with 10 percent of the population today," Fr. Finch told CNA.
Kevin J. Jones is a senior staff writer with Catholic News Agency. He was a recipient of a 2014 Catholic Relief Services' Egan Journalism Fellowship.