The Defense of Arcadia in 370

This chapter studies the Defense of Arcadia in 370. During the summer of 370, the Arcadians formed a formal koinon known as the Arcadian League. At the very interface of the transition from ethnos to koinon, the Arcadians had to face a Spartan-led invasion that threatened the existence of their nascent league. The Arcadians' response to this invasion—the Defense of Arcadia—was the first collective action of the Arcadian League documented in a contemporary source. But past scholarship has virtually ignored the dynamics and greater significance of this encounter, leaving a series of questions open for investigation. Was it the case that the founding of a formal league finally enabled widespread collective action in Arcadia? Was the organized force of Arcadians opposing the Spartan invasion of 370 a federal army? The chapter seeks to answer these questions by reconstructing the intricacies of the Arcadians' defense. Such an approach reveals that the Arcadians enacted a sophisticated defensive strategy that existed before the invasion of 370. This strategy made use of the basic infrastructure of the region, exploited a number of geographical and tactical advantages, and relied on the cooperation of civilian populations to observe, control, menace, attack, and ultimately drive off the invading army.