This thesis investigates the theory and practice of defence diplomacy, a term synonymous with traditional, state-centric diplomacy. Defence diplomacy commonly invokes images of a member of the armed services (man or woman) is full dress uniform among a sea of civilians within an embassy in a foreign country. These people are called Defense Attaché’s (DATT). Despite being a regular feature of diplomatic relations between countries, little is known. The DATT is attached by the sending state he or she represents to an embassy or consulate and charged with the primary responsibility of advising the ambassador on relevant military issues within the host nation (HN). They also serve as a staff contact and liaison within the embassy for military issues, as well as observing and reporting on military developments (Intelligence) in the host country. A distinguishing feature of the DATT, an invaluable ‘link’ in the information chain for the relevant state, is the aiguillette: braided gilded cords worn to distinguish special and senior appointees from senior officers. provides a comprehensive theoretical and practical review of this understudied yet important and evolving role. It argues that contemporary defence diplomacy is much broader and deeper than this common perception. The misconception is due in part, to a lack of theoretical grounding in analyses to date, which are predominately focused on practice; the ‘who’ and ‘what’ as opposed to the ‘how’ and ‘why’. A revised theory of defence diplomacy based on a strong theoretical foundation not only addresses the ‘why’ question, it also enables a comprehensive assessment of contemporary defence diplomacy, the ‘how’.