This book proposes that the practice of naval intelligence—and specifically HUMINT—was an effect of the duality of strategic priorities driven at the national level, often clashing with established norms and parochialisms within the Fleet, which often led to institutional change. At one level, the overall value of intelligence was an outgrowth of the institutional belief that the Navy’s purpose within the Western strategic narrative is to project power and influence, while holding true to Western democratic values. Navies of great powers, such as Great Britain and the United States, did this throughout the twentieth century. On another level, HUMINT in the Fleet was an effect of radically and periodically changing priorities at the national level (i.e., those affecting grand strategy and foreign policy), while leaders continued to rely heavily on the Navy—through its forward-deployed positions—to collect meaningful intelligence and enable decision-making in relation to adversaries.   From the emergence of radio technology and its use in intelligence collection during World War I, navies began focusing much of their intelligence collection efforts in the communications domain. Nevertheless, the reality of naval intelligence requirements could not ignore HUMINT (then, and into the early Cold War, generally referred to as espionage) because when technological means failed, naval officers still needed to obtain critical information. This book assesses the HUMINT in crises and determines the Navy and Marine Corps’ role in each. It traces naval HUMINT over a rapidly changing period in the Asia Pacific, the institutional and operational milestones during each unique period, and the overall impact intelligence had on the Fleet’s role in each crisis documented. Those include: the Navy and Marine Corps’ presence in China during the Second Sino-Japanese War (1931-1941); U.S. Presence in China during WWII, and the Chinese Civil War (1942-1949); the Taiwan Crises 1954-55 and 1958; and Kennedy–Johnson containment policy in Indochina (1961–1965). Ultimately, the research reveals that, at times, the use of HUMINT greatly influenced the ability to enable decisions in crises, but this fact was ultimately marginalized due to institutionalized biases that undermine the importance of intelligence on purpose. While this makes sense broadly, intelligence collection and analysis are not often associated with the lynchpin of naval battles but rather as part of the conditions prior to battle, or in political attempts to avoid conflicts.