For most of the 20th century, the US military culture (notwithstanding the Marines work in small wars) generally embraced the big conventional war paradigm and fundamentally eschewed small wars and insurgencies. Thus, instead of learning from our experiences in Vietnam, the Philippines, the Marine Corps experience in the Banana Wars, and the Indian campaigns, the US Army for most of the last 100 years has viewed these experiences as ephemeral anomalies and aberrations-distractions from preparing to win big wars against other big powers. As a result of marginalizing the counterinsurgencies and small wars that it has spent most of its existence prosecuting, the US militarys big-war cultural preferences have impeded it from fully benefiting-studying, distilling, and incorporating into doctrine-from our somewhat extensive lessons in small wars and insurgencies. This article starts by briefly examining some of the salient lessons for counterinsurgency from Vietnam and lists some of the sources for lessons from that war that have been neglected or forgotten. This article also examines some sources and lessons of counterinsurgencies and small wars predating Vietnam.