Mont-César was known as an "intellectual abbey" and Dom Bruno was allowed to complete his studies concentrating on the writings of Saint Irenaeus, a second-century Father of the Church.
His lecturing duties were cut short, the maverick monk was given a new assignment: mentor of the young son of the Duc de Guise, a claimant to the throne of France, living in Belgium.
During a stay in Hitler's Germany lecturing Catholic youths, he first witnessed what he would later characterize as the "shocking, revolting and nauseating" injustice and brutality of Nazi anti-Semitism.
In the wake of the 1939 German invasion of Poland, which sparked World War II, Belgium mobilized and Dom Bruno was assigned to be the chaplain of the 41st Artillery Regiment.
In the course of the campaign, he sustained a leg injury and spent the next six months in prisoner-of-war camps at Wolfsburg and Doessel, Germany, where he continued to provide religious and moral support to fellow prisoners.
The priest soon became aware that the home was being used as a hiding place for a number of Jewish adults and children, brought there by a group of Christians opposed to the Nazi policies.
In undertaking the dangerous mission of rescuing as many Jews as possible from deportation, Dom Bruno found support among fellow monks at Mont-César, higher-ups in the Belgian church hierarchy, and even several family members, including his young nephew Michel Reynders (who was later knighted in Belgium).
In addition to building and running his "underground railroad", Dom Bruno ensured that his charges were provided with false identification, including non-Jewish sounding names, and fake ration cards, as well as financial assistance to the rescuers.
During the Nazi occupation, Dom Bruno opposed the active conversion of his charges, but afterwards took the position that each case should be evaluated individually with the best interest of the child being the deciding factor.
At the war's end, he briefly returned to Mont-César, but was reassigned by his order to perform pastoral and educational work at other locations in Belgium, France and Rome.
No longer burdened by his wartime self-imposed rescue mission, Dom Bruno resumed his studies of Saint Irenaeus' legacy and in 1954 published the definitive lexicon on the subject.
[3] In 1964, the state of Israel proclaimed Dom Bruno Reynders one of the "Righteous Among the Nations", an honour bestowed on gentiles who risked their lives to help Jews during the Holocaust.