In 1914, shortly after Germany invaded neutral Belgium, the German authorities exacted revenge for the shooting of several of their soldiers on patrol in Louvain. They executed more than 200 civilians, then methodically set fire to homes and to the University of Louvain’s library. About 250,000 books went up in flames, including 800 that had been printed before the year 1500. Rebuilt and lavishly restocked between the wars, the library once again went up in flames in May 1940, the result of German shelling in World War II.