The U.S. Army / Marine Corps Counterinsurgency Field Manual was written to fill that void. The result of unprecedented collaboration among top U.S. military experts, scholars, and practitioners in the field, the manual espouses an approach to combat that emphasizes constant adaptation and learning, the importance of decentralized decision-making, the need to understand local politics and customs, and the key role of intelligence in winning the support of the population. The manual also emphasizes the paradoxical and often counterintuitive nature of counterinsurgency operations: sometimes the more you protect your forces, the less secure you are; sometimes the more force you use, the less effective it is; sometimes doing nothing is the best reaction.