in 1945, henry began a 20-year collaboration with artist wesley dennis. "i had just finished writing "justin morgan had a horse"," she recalled, "and wanted the best horse artist in the world to illustrate it. so i went to the library, studied the horse books, and immediately fell in love with the work of will james and wesley dennis. when i found out that will james was dead, i sent my manuscript to wesley dennis." henry and dennis eventually collaborated on nearly 20 books.