The Department of Defense operates in a challenging natural environment stretching from the surface of the earth into the far reaches of space. While the environment has beleaguered military operations for centuries, it has also provided strategic, operational, and tactical advantage to the forewarned. Sun Tzu once proclaimed, "Know the ground, know the weather; your victory will be total." Indeed, history has shown that commanders who have exploited knowledge of the environment and its effects have been rewarded with victory, while those who have ignored the environment have often met with failure.