Defensive imperialism

Defensive imperialism is a theory of imperialism viewing security as the prime motive of imperialism. The view originated in Roman studies in the late 19th century and is perhaps the oldest of theories explaining Roman imperialism. It is closest to the argument favoured by Romans themselves and their Greek admirers, and continues to have support in our days. According to the most notable critic of the thesis, William Vernon Harris, no other overall theory about Roman imperialism in the Middle Republic has received as much support from Historians.

Until the 1970s, it was widely held that the Romans did not have an aggressive, expansionist policy towards the rest of their world. Rather they built their Empire in self-defense, or in defense of their allies. Facing powerful neighbours who threatened its security or even existence, Rome responded to ward off the peril. The Roman responses ranged from taking preventive offensive action to taking control of the beaten enemy to preclude a revanche. The Romans repeatedly conquered kings and peoples, but then took no steps towards the consolidation of imperial rule. They were not therefore conscious imperialists and the Roman Empire was irrational rather than planned outcome.

The theory draws its strength from the apparent inconsistency of Roman foreign policy, the slowness with which their rulers acted (or reacted), and their reluctance to annex. In this pattern economic and ideological factors appear secondary at most. Key evidence for the view is derived from Second Punic War, Roman policy towards Greece at least down to 148 BC, and towards the Near East until 66 BC. In the chapter, titled "Defensive imperialism," Howard Hayes Scullard claims that in the initial war with Carthage, the first and crucial step in Rome's expansion outside Italy, the primary motive was the defense of Italy from the immediate Carthaginian threat rather than territorial conquest.

According to John Rich, the doctrine originated with Theodor Mommsen in 1877. Later, Tenney Frank, Maurice Holleaux and Ernst Badian added the main terms of the view. Beginning with the antithesis of William Harris in 1979, the theory of defensive imperialism has been mostly criticized and interpreted as justification and apology of imperialism by the contemporary Western Colonialists. Later, the concept of apology was challenged.