This paper examines the British response to the crisis that resulted from the Iranian decision to nationalise the Anglo-Iranian Oil Company in 1951.The British government contemplated the use of military force from the outset of the crisis and a series of plans were developed. Unfortunately, in a manner similar to the Suez Crisis five years later, the military were unable to provide a suitable response until political considerations had made the use of force unattractive. Despite this, the Foreign Secretary, the Minister of Defence, and the Chiefs of Staff continued to press for an armed response. This paper uses newly released archival sources to examine the military plans and preparations and to analyse the way in which these interacted with political considerations to undermine the British position in Iran.