Abstract: Empire by treaty is one of the defining features of British imperialism in the Middle East in the inter-war years. In 1928, Transjordan, which was part of the Palestine mandate of the League of Nations, was given a separate status thanks to an Anglo-Transjordanian treaty which defined the respective roles of Britain and of the Transjordanian government, nominally led by amir Abdullah since 1921. Transjordan shared its northern border with Syria, which was governed by the French, also as a mandate. Based on the archives of the political cabinet of the French High Commissioner in Beirut, and especially on a lengthy and minute report about the 1928 Anglo-Transjordanian treaty written by Lieutenant Pierre Rondot, an officer in the Services Spéciaux au Levant, the paper will analyse the ambiguities of the French perception of the treaty. While they denounced what they saw as the hypocrisy of the British, who used treaty-making to claim that their policy was liberal because based on cooperation, the French also had to recognise that the treaty was a sophisticated and very effective instrument of colonial policy which eventually inspired them to renegotiate their relationship with the Syrian nationalists a few years later. By highlighting this mimetic pattern and the connectivity between colonial empires, the paper intends to contribute to the field of transimperial studies.