One of the most difficult security challenges of the post-Cold War era has been stabilizing failing states in an era of irregular warfare. A component of the strategy to address this problem has been security force assistance where outside powers train and advise the host nation's military. Despite billions spent, thousands of advisors, and innumerable casualties, the American efforts in Afghanistan and Iraq failed. Among those colossal military disasters were pockets of success.

Frank K. Sobchak explores security force assistance across five case studies, examining what factors were most critical for U.S. Special Forces units to build capable partners. The book assesses the impact of five components of Special Forces advisory missions: language training and cultural awareness; the partner force-to-advisor ratio; the advisors' ability to organize host-nation forces; whether advisors are permitted to guide in combat; and the consistency in advisor pairing.

Sobchak argues that the most crucial factors in producing combat-effective partners are consistency in advisor pairing and maintaining a partner force-to-advisor ratio of twelve special forces soldiers advising a company-sized force or smaller. Many of these findings could be used to improve the odds of success for larger security-force assistance missions.