This paper explores the impact of the US military assistance on the Turkish military during the early Cold War years. Military transformation and international security assistance have become popular subjects for study due to new threats to international security and changing nature of warfare after 9/11. My paper focuses on an earlier experience of military transformation that was set off by the US military assistance to Turkey under the Truman Doctrine in 1947. Although Turkey was one of the first two countries that hosted American military missions in the wake of the Second World War, the transformative impact of the American military assistance there has merited little, if any, attention from military historians or security studies scholars. After 1947, massive influx of US military hardware into Turkey required fielding of a sizeable number of American advisors/trainers. They were subsequently drawn into the task of re-casting the Turkish military along the American way of war. The task proved to be difficult, formidable and not without clashes between the two military cultures. Formerly shaped under the Prussian/German influence, some senior officers attempted to resist the transformation, while majority in junior ranks felt empowered as a result of their newly acquired mastery of the American methods, techniques and language. This paper attempts to assess the impact of this transformation experience in terms of change and contunity in military training/education, organization, conceptualization of war, interservice and civil-military relations in Turkey. It concludes that the US military assistance also played a catalyst role in the generational change of the Turkish military, as the 27 May coup resulted in a large scale purge of the "Prussians" from the ranks. My research mainly draws on the papers of the Joint United States Mission for Military Aid to Turkey (JUSMMAT) at NARA, which are complemented with official publications, memoirs of military officers and author's interviews.