The writings of the Belgian historian Jean Henri Otto Lucien Marie Pirenne (1862-1935) renewed 20th-century ideas about the origins of European cities. His teaching created a major school of Belgian medievalists.

Henri Pirenne was born at Verviers on Dec. 23, 1862. At the University of Liège he studied history with Godefroid Kurth and Paul Fredericq. He received his doctorate in philosophy in 1883 and won a scholarship that allowed him to study in Berlin and Paris. In 1885 he organized the teaching of paleography and diplomatics at the University of Liège, and in 1886 he was named professor at the University of Ghent, where he remained for 40 years.

During World War I Pirenne was imprisoned for resisting the German occupation. Moved from prison camp to prison camp, he learned Russian in one, taught Belgian history to the Belgian prisoners in a second, and without the aid of books or...