Book excerpt: An environmental journalist reveals how some California military bases are leading the charge in the fight against climate change. In California, the US military has begun to redefine how our national security operations relate to the destabilizing effects of climate change. Several bases have taken on a largely unrecognized yet crucial role in renewable-energy innovation and in preserving cultural and natural treasures. These facilities are going beyond environmental stewardship to align national defense with energy security and the protection of endangered species. In Unlikely Ally, environmental journalist Marilyn Berlin Snell takes readers through these bases to examine what twenty-first-century sustainable-energy infrastructure looks like; whether combat readiness and species protection can successfully coexist; how cutting-edge technology and water-conservation practices could transform life in a resource-constrained world; and how the Department of Defense's scientific research into the metabolic secrets of the endangered desert tortoise could speed human travel to Mars.