Organizers for a Yosemite National Park mountain hike are seeking volunteers to plan and support an annual event that commemorates the sacrifices made by service members fighting in the Global War on Terrorism. The Lewis B. Puller Memorial Hike, which takes place annually the first week in August during Purple Heart Day, is an eight-mile trek up Half Dome in the Sierra Nevada Mountains in California. - Organizers for a Yosemite National Park mountain hike are seeking volunteers to plan and support an annual event that commemorates the sacrifices made by service members fighting in the Global War on Terrorism. The Lewis B. Puller Memorial Hike, which takes place annually the first week in August during Purple Heart Day, is an eight-mile trek up Half Dome in the Sierra Nevada Mountains in California.