This chapter examines the dramatic transformation of international priorities governing the purpose and principal uses of military force over the past 25 years. It distinguishes the broader historical background of armed humanitarian intervention (AHI) prior to 1989 from two subsequent, distinctive phases: a second wave of humanitarian crises and responses during the 1990s, and a more recent third wave of ethical analysis, dominated by proposals for new political arrangements that would govern collective decision-making by the international community when faced with the question of whether to deploy their military forces for the prevention or cessation of humanitarian crises. The manner in which the history of AHI is narrated is strongly dependent upon the perspectives from which AHI efforts themselves were experienced. All of the military interventions proposed or carried out for humanitarian purposes in the 1990s, however noble their intent violated every single provision of that Weinberger-Powell doctrine.

This chapter argues for what the author calls the justification-based account of humanitarian intervention, according to which the permissibility of humanitarian intervention is determined by two central criteria. The first is that there exists a sound justification for intervention, roughly, that there is a threatened or ongoing process of widespread and serious rights violations that can be averted only by military force and such force is proportionate. This criterion can be satisfied ad bellum. The second criterion is that the actions of interveners are reasonably expected to aid. This criterion applies largely to the in bello behavior of the intervening state. One of the difficulties in making sense of the debate about how to identify humanitarian interventions lies in distinguishing the various components of behavior, motives, intentions, actions, ends, and outcomes.

Philip, Alexander and later Hannibal can be regarded as military commanders of genius, capable of guaranteeing the command and control of a heterogeneous military force. As the territory of the Macedonian state grew, Philip was able to expand its demographic and financial base. The expansion of the Macedonian and Roman manpower bases, which in turn enabled military and territorial expansion, was due to a willingness to extend citizenship and to incorporate allied contingents fully into their military structures. Although Macedonia had some of the best sources of shipbuilding timber in the eastern Mediterranean, neither Philip II nor Alexander embarked upon major programmes of warship construction. The standard warships of the Hellenistic period needed crews of c. 150-300, or more in the case of the larger polyremes. During the Second Punic War the Carthaginian naval effort was not as extensive as that of Rome, but it was still far from negligible.