A Dog of Flanders
In the 1960s, Clark frequently collaborated with producer Robert B. Radnitz. Throughout the late 1950s and the 1960s, Clark continued to direct films, although just 15 pictures bear his name. His most popular and critically praised motion pictures focused on people's relationships with animals and the wild: "A Dog of Flanders" (1959), "The Sad Horse" (1959), "Misty" (1961), "Flipper" (1963), "Island of the Blue Dolphins" (1964), and "My Side of the Mountain" (1969). "A Dog of Flanders" was widely praised for its performances and lush, painterly cinematography, while "Flipper" proved highly popular and led to a long-running television series (with which Clark was not associated).