History humbles us—hence the reason we continue to ignore Clio’s lessons. Dr. O’Hanlon’s superb book, however, returns Clio to her indispensable role for the strategist and policymaker, whilst also reminding us that to prepare for future (and inevitable) conflict, we need to learn from our past. Dr. O’Hanlon’s book serves as a welcome primer to guide undergraduate and graduate classrooms alike in understanding that without history’s instruction we will fail.

Melanie Sisson, Fellow, Strobe Talbott Center for Security, Strategy, and Technology, Brookings Institution

A brilliant, yet sobering overview of modern war by a uniquely qualified and thoughtful expert. Michael O’Hanlon put conflicts from the Civil War to Afghanistan into strategic context with a concise clarity that is fascinating for veterans of past wars, and fundamental for strategists of the future. His final chapter’s ‘Three Lessons’ should be required reading for policymakers.

Stanley McChrystal, former commander, International Security Assistance Force (Afghanistan), U.S. Joint Special Operations Command

In this timely, intriguing and readable book, Michael O'Hanlon casts the eye of a contemporary strategist over America's past wars to consider their origins and conduct, and what they tell us about how to prepare for future wars, warning especially about the dangers of falling into the trap of overconfidence.

Lawrence Freedman, Emeritus Professor of War Studies, King's College London

In Military History for the Modern Strategist, Michael O’Hanlon demonstrates once again why he is one of the outstanding defense analysts of our time. He has astutely recognized that at a time of profound strategic uncertainty and change, the smartest thing we can do is to go back to basics: start with the military history of our nation over the past century and a half and build upon its lessons to fashion a new grand strategy that can carry us through the coming era. It is a brilliant approach, and he has executed it marvelously well in these pages. Here he provides all of the key information and insights from America’s major conflicts since the Civil War in a way that is both elegant and concise—precisely right as the basis for new strategic thinking.

Kenneth Pollack, Senior Fellow, American Enterprise Institute

Michael O’Hanlon has created a unique American military history primer for policymakers that particularly emphasizes two great truths: wars never proceed along the path belligerents expect, and quick, cheap victories are extremely rare.

Conrad Crane, research historian, Army War College, author of Cassandra in Oz: Counterinsurgency and Future War and American Airpower Strategy in World War II