When the city-state of Rome began to exert her influence throughout the Mediterranean, the ruling classes developed friendships and alliances with the rulers of the various kingdoms with whom contact was made. During the great military struggles which heralded the end of the republic, it became clear that the general who could count on the clientship of the powerful kingdoms within Rome’s sphere of influence would have a decided advantage over less fortunate rivals. Moreover when Octavian, later Augustus, became the sole ruler of the Roman world after the battle of Actuim, these client kingdoms were an important factor in the defence of the Roman Empire, and Octavian insisted that their kings became personal clients of the emperor. Augustus saw beyond the former uses of these kings, as military supporters in battles fro supremacy, and realized their full potential to a unified empire – some client states he used as buffers against more remote hostile nations, others protected trade routes and others maintained a sense of national identity, whilst introducing the Pax Augusta to their troublesome subjects. At the same time the emperor realized the annexation of some of these kingdoms was necessary and desirable, and so the gradual transformation of kingdoms into provinces began. Augustus' successors found that their predecessor, who had inherited so many small but potentially powerful clients, had set a good example in dealing with them. The Julio-Claudians and Flavians continued the process of romanization and annexation, and new clients were only contemplated when the legions needed support or a respite from warfare; only in Armenia did the clientship pose problems. Trajan, the warrior-emperor, was the first to attempt to annex all his clients and his failure showed the wisdom of Augustus' settlement - a settlement which lasted for several centuries
