When T.R. Fehrenbach famously penned, "You may fly over a land forever; you may bomb it, atomize it, pulverize it and wipe it clean of life-but if you desire to defend it, protect it and keep it for civilization, you must do this on the ground, the way the Roman legions did, by putting your young men into the mud," he was writing about another time, another war and another part of the world, Korea. As far as Thomas Donnelly and Frederick Kagan, two veteran Washington defense analysts at the American Enterprise Institute, are concerned, the line still sticks today. 

 The truth in Ground Truth: The Future of U.S. Land Power is that America must have ground forces second to none; without an immediate change in policy, however, that is not going to happen. The pressures of the Long War and a long record of post-Cold War neglect are turning the U.S. military into a hollow force. The answer the authors offer is a bigger budget. The costs are high, about $240 billion. The consequences of failing to invest, they argue, are even costlier. They are probably right.

Ground Truth makes the case for paying more attention to ground forces. In concise, jargon-free and fast-paced chapters Donnelly and Kagan ask sensible questions and offer commonsense answers. Why are we in trouble? Why do we need a better military? What kind of future wars will we fight? What kind of military do we need? How much will it cost? The answers are revealing. America took a post-Cold War peace dividend that left the Army and Marine Corps too small for the terrors of the post-Cold War world. Donnelly and Kagan provide a fair and sober assessment of the current state of play-the state and nonstate threats that more than make the case for military preparedness. In the most convincing section of the book, the authors point out the folly of trying to predict the precise nature of the next conflict and use fortunetelling as an excuse to scrimp on force structure. Not surprisingly, they opt for a capabilities-based force that can effectively conduct a range of missions, from rooting out insurgents to battling conventional battalions. Ground Truth concludes it will take 10 years to build a ground force of about two million active and reserve soldiers and marines.

Of all the future plans being touted for the military beyond Iraq and Afghanistan, Donnelly and Kagan unquestionably offer one of the most ambitious. The precise blueprint they offer can and should be debated, but their defense of landpower in the 21st century is impossible to ignore.

The taproot of Ground Truth is a series of case studies in contemporary military history that illustrate why Fehrenbach's dictum is as true as ever. These include an. engrossing study of the operations of Col. H.R. McMaster's Third Armored Cavalry Regiment in Tal Afar in 2005, which describes how well-led conventional forces adapted to unconventional warfare. Other studies include an analysis of the invasion of Iraq, post-conflict combat in the Sunni Triangle, Israel's recent war with Hezbollah and support of antiterrorism operations against Abu Sayyaf in the Philippines.

Having made their case for landpower, Donnelly and Kagan counter fiscal naysayers that while much more baseline defense spending seems like a good deal of money, "in the context of the overall U.S. economy, the sticker shock diminishes. The United States will produce about $14 trillion worth of goods and services in 2008." Even their robust bill for defense spending requires only about a single percentage point of GDP to conduct the government's most fundamental responsibility-providing for the common defense.

Concerning defense spending, Ground Truth is on solid ground. America is in for a long war-it should be prepared to pay for it. The good news is that compared to the last long war, the Cold War, the relative burden is more than bearable. What Ground Truth does not dwell on is all the needs of the other services-which are significant as well. This makes the issue of adequate defense spending even more pressing. The greatest military disaster would be insufficient defense budgets that force the services to squabble over scraps. That is a military hardly worth having.

James Jay Carafano is a senior fellow at The Heritage Foundation and the author of GI Ingenuity: Improvisation, Technology and Winning World War II.