Useful insights into the operation of the master principle, and its problematic elements, may be gained by examination of three instances where particular groups in different ways challenged this premise, claiming to override it with a higher principle: the right to self-determination. This chapter presents the three cases, Katanga, Biafra, and Eritrea, which are not the only such instances; the clash between territorial integrity and self-determination is also encountered in the greater Somalia movement and the Western Sahara conflict. It provides comparative examination to the conceptualization of the unit laying claim to independent status, the justifications for this claim, the ways in which the sovereignty demand was pursued, and the responses of the international system. The chapter deals with the Katanga case, because it was first to acquire international visibility. The roots of the separatist idea extend back to the early years of the colony, and the remoteness from the headquarters of colonial administration at Kinshasa.