Chapter 2 examines the traditional view of superfluous injury or unnecessary suffering (SIrUS) in the context of the law of armed conflict (LOAC), emphasizing the historical interplay between humanitarian considerations and military necessity. This chapter analyzes key milestones, including the Lieber Code, the Hague Conventions, and customary principles, such as distinction and proportionality, to illustrate the evolution of SIrUS as a restraining norm in warfare. The chapter introduces and underlines a traditional viewpoint that balances achieving military objectives vis-à-vis the suffering or injury caused by weapons, asserting that harm is deemed unnecessary solely when it does not secure an essential military advantage. This chapter highlights the impact of these traditional interpretations on the legal definitions and the prohibition of specific weapons, creating a basis for current challenges in applying SIrUS to modern warfare.