Resumen: This paper deals with the life and professional career of the Chilean diplomat James Holger Blair (19282014), who performed various tasks for the Chilean foreign service. His duties took place in the context of the Cold War and its immediate aftermath. The work uses the approach of the new Diplomatic History and is based on unpublished and cardinal primary sources of the General Historical Archive of the Ministry of Foreign Affairs of Chile, specifically the James Holger B. archive, the United Nations archive, the digital archive of President Patricio Aylwin, Chilean and German newspaper sources, complemented with secondary sources of high academic quality that have comprehended with the international historical context where this agent of Chilean diplomacy was involved.