Von Hassler's career flourished in the Land of Enchantment, and he became well-known for his ability to capture the area's dramatic seasonal changes with a gentle, tightly controlled palette.
"Nature is a great teacher," he told a reporter in 1961. "To be a truly good artist, one has to be first a naturalist. Each area presents its own background and feeling. Unless you get the feel of a place, your painting will lack strength and beauty."
By the 1940s, von Hassler was a teacher to many emerging artists in the area. They referred to him as The Dean of Albuquerque Artists. A large mural commission by the artist is still on display at the Albuquerque Sunport.