The triptych form's transportability was exploited during World War Two when a private citizens' committee in the United States commissioned painters and sculptors to create portable three-panel hinged altarpieces for use by Christian and Jewish U.S. troops for religious services. By the end of the war, 70 artists had created 460 triptychs. Among the most prolific were Violet Oakley, Nina Barr Wheeler, and Hildreth Meiere.