In 1941 the National Park Service established 16 camps for recreation and healing for servicemen. Nature's physical and mental healing power was an 'X-factor' for military medicine.
By war's end over 33 camps were set up in National Parks across the US with a capacity to house 20,000 men. The NPS emphasized the opportunities to find inspiration and "healthful" exercise in the parks. "For soldiers and civilians who need respite from grueling war service," noted one article, "the National Park Service can offer spiritual and physical rehabilitation."