One of the most important aspects of Byzantine diplomatic and military manoeuvring—thoroughly legitimated in all the military treatises—was the avoidance of fighting wherever possible, as we have seen. Strategy was designed not just to protect the state with physical force; a primary feature of imperial strategic thinking was to deter possible aggression by making the potential losses on the part of the aggressor appear unacceptable before the first blow was struck. The policy of avoidance which characterizes warfare in Asia Minor in the period c. 650–730 was certainly forced upon the empire by the situation, but the empire’s political and military leaders were able over several generations to turn this into a positive feature, so that regular raids and invasions became less and less profitable, to the point indeed where, by the later eighth century, they had as much a symbolic significance for the Arabs as any worthwhile political or even economic value. This was not necessarily a reflection of a continuity in strategic decision-making over the longer term (although it may have been—there is no real evidence), but it certainly represented the ways in which the empire’s military and fiscal structures responded, the methods through which individual emperors and their military commanders were able in the circumstances to exploit the resources at their disposal, and the realization that it was an appropriate way of defending the state’s territorial integrity. In the Balkans, displays of imperial military might served similarly to dissuade planned hostile attacks, or to encourage—as in the situation during the 860s— the development of a particular political-cultural alliance. Such a policy was encouraged by the fact that, in contrast to the situation in the east, it was the empire which, generally, had a greater availability of resources, even if manpower was always a problem. This relative superiority—expressed both tactically on the battlefield and in terms of logistical arrangements—was frequently employed to discourage aggressive action.

Deterrence could also take a more militarily active role, however: punitive expeditions, intended to destroy the opponent’s will to fight in the future as well as his resources and his organization for warfare, were also a feature of Byzantine strategy—most obvious, perhaps, in the Bulgarian expeditions of the emperor Constantine V, but evident also in the raiding which Byzantine commanders carried out along the eastern frontier at various times. The dangers inherent in this approach, however—that an equally powerful response might be provoked, with consequences for the empire’s own military and economic situation—meant that such action was usually undertaken only when the enemy was in no condition effectively to respond. The intelligent exploitation of political difficulties inside the hostile polity, and the crucial importance of the various means for collecting and assessing information at the government’s disposal, becomes especially clear here.