Karl Leisner (28 February 1915 in Rees – 12 August 1945 in Planegg, Germany) was a Roman Catholic priest interned in the Dachau concentration camp. He died of tuberculosis shortly after being liberated by the Allied forces. He has been declared a martyr and was beatified by Pope John Paul II on 23 June 1996. Life Leisner was born on 28 February 1915, the oldest of five children. When he was six years old, the family moved to Kleve, a city on the lower Rhine, where his father worked as a civil servant. He attended school and completed his gymnasium studies in 1934. During his youth, he became an altar boy and, at the suggestion of the high school chaplain, formed a Catholic youth group, the Saint Werner Group. These youth groups combined prayer with outdoor activities, such as camping and cycling. Leisner turned out to be a natural leader and became a youth leader in the 1930s, during the era in which the Nazis were beginning to take control of all youth organizations. In order to avoid Nazi interference, Leisner would often take his group on camping trips to Holland or Belgium. In 1934, when he was nineteen, Leisner entered the seminary in Munich, and was named Diocesan Youth Leader by Clemens August von Galen, Bishop of Münster. He spent six months in compulsory agricultural work during which, despite Nazi opposition, he organized Sunday Mass for his fellow workers. His home was raided by the Gestapo, who seized his diaries and papers. These meticulously preserved documents tell how the spiritual young man became a religious leader. On 25 March 1939, Galen ordained Leisner a deacon. Shortly after his ordination, during a medical examination, the doctor told the new deacon that he had contracted tuberculosis. In those days, the sole treatment available for the disease was good food and fresh air. These were to be found at a sanitorium in St. Blasien, in the Black Forest, where he was sent and began to recover. It was during his recovery that a fellow patient heard him criticize Adolf Hitler. The Gestapo arrested him as a political prisoner on 9 November 1939, when he was twenty-five. He was interned first in Freiburg and later in Mannheim. Leisner was initially imprisoned in the Sachsenhausen concentration camp, but was moved to the Dachau concentration camp on 14 December 1940, where he became prisoner No.