The investment protection treaty concluded between Germany and Pakistan in 1959 is generally regarded as a milestone in the development of international investment law. It has entered the collective memory as the first bilateral investment treaty (BIT). In this article, we analyse archival sources to investigate what makes this treaty the first of its kind and why it was Germany that concluded this agreement at that specific time. Through historical analysis, we outline how previous instruments of investment protection influenced the creation and design of the BIT. In this context, continuities with legal practices and patterns of argumentation of the colonial period become apparent. In addition, we trace the ideas driving the BIT and its negotiation process. Considerations of economic policy in the context of immense trade surpluses were crucial. The emergence of the first BIT was moreover closely linked with domestic legal instruments, such as the federal investment guarantee scheme (Bundesgarantien). In short, German BITs should be understood as an appendix of the budget acts. Throughout, we highlight the extensive influence of the financial industry – especially via Hermann Josef Abs.