Circle the Wagons: The History of US Army Convoy Security is the 13th study in the Combat Studies Institute (CSI) Global War on Terrorism (GWOT) Occasional Papers series. Transportation Corps Historian Richard Killblane's manuscript on convoy security is another case study modern military professionals can use to prepare themselves and their soldiers for operations in the current conflict. This work examines the problems associated with convoy operations in hostile territory and the means by which units can ensure they are ready to deal with an enemy ambush or assault. Killblane provides a brief overview of the US Army's experience in convoy operations and convoy protection from the period of the War with Mexico up to and including the current conflict. He then presents an indepth look at the development of "hardened convoy" tactics, techniques, and procedures (TTPs), focusing on the 8th Transportation Group's experiences in Vietnam. That group had the dubious honor of conducting its missions along Highway 19, arguably the most dangerous stretch of road during the Vietnam War. Killblane describes the group's initial experiences and how, over time, various commanders and soldiers developed methods and means of defeating the enemy's evolving tactics. The hardened-convoy concept is one that, frankly, receives little attention by Army leaders in peacetime-the lessons from which each new generation of soldiers seems painfully destined to relearn. Logisticians, contractors, and those military leaders responsible for such operations in the current struggle against terrorism will gain useful knowledge for developing hardened-convoy TTPs from this occasional paper. More important, we at CSI desire that this study be read by future generations of leaders, before they have to conduct such operations, so that their mission and the soldiers entrusted to them will prosper from the lessons of the past.