<論説>アクティウムの海戦再考

Abstract

前三一年に、オクタウィアヌスがアントニウス・クレオパトラ連合軍を破り、ローマ世界の単独支配者となった戦いは、「アクティウムの海戦」として古来有名である。ところが、史料のほとんどが、勝利者側の主張しか伝えていないために、この事件の真相を解明することは非常に困難である。アクティウムを頂点とする両陣営の抗争は、従来は主にローマ帝国内部の権力闘争として把握され、オクタウィアヌスが宣戦を布告した相手が、アントニウスではなくてクレオパトラであったことも、「外征＝正統な戦争」を標榜するための口実であるとされて来た。しかし、史料を再検討した結果、この戦争が本質的にもローマとアレクサンドリアの対立であり、当時の地中海世界におけるエジプトの卓越した経済力が、この事件の大きな要因の一つであったことが知られる。エジプトにおける、前二世紀以降の南海貿易の発達と、地中海方面の貿易の拡大にともなって、ローマとアレクサンドリアの貿易関係は、ローマ側の大幅な輸入超過となっていたのである。

The true history of Antony and Cleopatra is gone beyond recall; ancient writers, as well as modern historians, had little sympathy for the defeated. However, as for the Battle of Actium, a few fragmentary facts can be discriminated from the fabricated version of victors, which give us clue to the problem. In this article, therefore, I start from examining the contemporary evidences about Actium, to make it clear why and how the war broke out. Octavian made war upon Cleopatra, not upon Antony, i.e. Rome fought against Alexandria. Then, Actium was really not so great a battle, but was rather a fiction of the victor's side. The intention of Antony and Cleopatra, I think, was an economic blockade of Italy. They must have supposed, by shutting up Italy by sea, Rome would soon fall into disorder; because Italy had to import its corn, and Octavian's war chest was scarce. But contrary to their expectation, Italy and the western provinces united under Octavian, moreover, their dull operations and the clever propaganda of enemies deprived Antony's troops of their fight. It is my object in this article, to point out an economic factor as one cause of this war. The balance of trade between Rome and Alexandria was always against Rome. A third of the annual corn's supply of Rome came from Egypt; and the need for oriental commodities, especially goods from Arabia and India, must have increased through the 1st century B. C. With development of sea-route trade on the Indian Ocean, the balance of trade must have gone still worse to Rome. Here I see the background of Actium, the ambition of Rome to annex Egypt, which was the then most important country in the Mediterranean world.