Dr. Kenneth Werrell's history of ground-based air defense performs an important service both to scholarship and, more importantly, to the defense of our nation's freedom. It is perhaps human nature that we tend over time to lose sight of the lessons of the past, especially when they do not conform to certain cherished preconceptions of ours. That such myopia can be dangerous, if not downright disastrous, Dr. Werrell's study richly illustrates. Without sentimentalism, he chronicles a pattern of lessons learned and too quickly forgotten as the marvel of air power was reminded again and again of its limitations and vulnerability. In Korea and in Vietnam, the American people were stripped of their illusions of national and technical omnipotence. The unhappy outcome of those two conflicts was doubly lamentable because the lessons of World War II were-or should have been-fresh in our minds. In that world war, as Dr. Werrell shows, relatively cheap ground-based air defense did make a difference: at Ploesti, at Antwerp, and at the Rhine bridges. And it will make a difference tomorrow. The greatest value of Dr. Werrell's work is that it provides guideposts and guidance for us as professional soldiers and aviators charged with upholding American security. We have taken history's lessons to heart as we plan and program our ground-based air defenses into the next decade and beyond. In both the forward and the rear areas, we have emphasized the time-honored principles of mass, mix, and mobility. No one weapon, not even today's modern aircraft, can do the job alone. The truism applies with particular force to antiaircraft defense. And at least one other truism emerges from Dr. Werrell's and our own studies: effective air defense requires a joint and combined effort. Our planning has been predicated on the assumption that counterair will play a central role in safeguarding our ground forces from air attack. On the ground, the air defense artillery will count on the cooperation and assistance of our colleagues in the infantry, armor, and field artillery. On our success or failure in working together to meet the challenges of tomorrow will rest our nation's future.