Henri Koehler was the brother of the late Father Theodore Koehler, director of the Marian Library at the University of Dayton, in Dayton, Ohio, from 1969-1987 (and continued to serve at the Marian Library until his death in 2001). The Koehlers were French, from the Alsace region. During Fr. Koehler's directorship at the Marian Library, he asked his brother, Henri, still residing in France, to write to French churches with Marian titles and request information such as photographs, articles, and brochures for the Marian Library collections.
From the guide to the Henri Koehler correspondence, 1982, (University of Dayton, Marian Library)