Thucydides’ The Peloponnesian War was written “as a possession for all time.” It has been taken as such by generations of political theorists and statesmen. Thucydides’ insightful description of the actions of the main players in the Peloponnesian War of 460-404 BCE and his fundamentally realist theories of international affairs continue to provide a good lens through which to view contemporary and historical international affairs. However, although the distribution of coercive power resources – the fundamental tenet of realism and the element emphasized the most by Thucydides – is of strong importance in international affairs, it is not of overriding importance. Thucydides recognizes that multiple lenses are necessary for interpreting international affairs, including the effects of non-rational decision-making, of states’ preferences, and of institutions. While he rightly accepts that all of these factors are important, he oversimplifies by taking coercive power capabilities as the bottom line. States’ preferences and the intensity of these preferences must be read as the most important factor in international affairs, generating a tolerance threshold. This threshold exists in the areas of power balancing and national security, commerce, specific colonies, ideologies, matters of prestige, and other areas. When a state’s action crosses one or more of these tolerance thresholds, conflict may ensue. For imperial powers like Sparta and Athens, that tolerance threshold includes strong preferences other than the purely the balance of power such as specific alliances, commercial advantage, and ideology.
In Thucydides’ theory of international affairs, the tolerance threshold of paramount importance is the balance of power. Thucydides’ core assertion is that “the growth of the power of Athens, and the alarm which this inspired in Sparta, made war inevitable.”
The changing balance of power in Greece, with a rising power challenging an establishing power, set the stage for conflict. For states, he argues, military contest is one way of achieving strategic goals. Athens and Sparta each desired to maintain a network of weaker states with whom they could trade and upon whom they could depend for military resources and tribute. To a great extent their interests were zero-sum: each desired to be a regional hegemon with the greatest source of tribute, trade, and resources.
Thucydides provides greater detail on Athens: as a growing imperial power, Athens faced the constant threat of revolt, “for the Athenians were very severe and exacting.” The very collection of tribute and ships, Thucydides tells us, inspired revolts that required further funds and ships to quash.
Athens’ desire to gain more allies and its competition with Sparta were based on the threat from within as well as the threat from without. Thucydides glosses over this important element, focusing mostly on the changing alliance structures and power relationships.
The alliances themselves were problematic. Rather than fostering cooperation and goodwill, they exacerbated the growing conflict between Athens and Sparta. Athens’ alliance with Sparta provided grounds for misunderstanding and offense, as the two sides only allied out of convenience and not out of strong shared preferences. Their alliance networks against each other also provided fertile ground for conflicts among the satellite states. Some states switched alliances; conflicts between others and especially among neutral states threatened to draw in Sparta and Athens as well.
It was just such a conflict between neutral Corinth and its colony Potidea (an ally of Athens) in 432 BCE that sparked military action.
Thucydides uses the evolving alliance structure to conceptualize the changing balance of power between states and to highlight the rapidity and seeming randomness of the initiation and escalation of major military conflicts.
Thucydides also describes the importance of the decision-making process in initiating conflict or maintaining peace, focusing on non-rational decision-making in the Congress of the Peloponnesian Confederacy in 432 BCE. Sthenelaidas, a Spartan ephor, challenged Sparta’s sense of honor and strength, calling to vote “for war, as the honor of Sparta demands, and neither allow the further aggrandizement of Athens, nor betray our allies to ruin.”
Sthenelaidas deliberately excites the congress and calls for a vote by acclamation, “the fact being that he wished to make them declare their opinion openly and thus to increase their ardor for war.”
Thucydides notes the strength of this strategy in achieving a desired decision but decries it through the words of Archidamus, an elder Spartan statesman. Archidamus praises moderation as honorable, saying, “self-control contains honor as a chief constituent, and honor [contains] bravery.”
For all of Thucydides’ discussion of power balancing and strategy – and for all of his own experience as a general – he prefers rational calculation to incendiary rhetoric.
Thucydides’ strategies of analysis of the Peloponnesian War and the theories he derives from it can be applied to an analysis of more recent events. His emphasis on the balance of power and acceptance of other secondary causes of conflict is not the most accurate way to view these events, however. An examination of the rise of the Concert of Europe; the 19th-century British Empire; and the outbreak of World War I through preferences and tolerance thresholds – including balance-of-power and ideological thresholds – is the most comprehensive manner of analyzing international affairs.
One of the most important elements in determining the courses of these three eras was the interactions of great powers and their subsidiaries. While it was beneficial for great powers to have colonies and weaker allies, these subsidiaries were also a liability. The Concert of Europe, an informal congress of 19th-century European “great powers,” was founded on the concept of smoothing conflicts by fostering communication about preferences and intentions. The Concert sought to publicize states’ tolerance thresholds and decrease the likelihood of thresholds being crossed. In early 19th-century Europe, the threshold of the greatest concern to the main actors were territorial. States conflicted over national borders and felt threatened by changes in each others’ power, most importantly by the growing power and imperial goals of Napoleon. After the defeat of Napoleon, the Concert divided up Napoleon’s spoils and created smaller states deliberately as buffers to decrease the strength of territorial thresholds. It also provided a means of communication and arbitration to provide alternate conflict-resolution strategies to war. Its goal in these and other agendas was to decrease the importance of the balance of power and instead establish “a political equilibrium based on the tacit acceptance by smaller powers of a general great-power hegemony.”
This was a move away from the potential of conflicts between smaller states or between one power and a smaller neighbor to spark a larger conflict. The Concert also stabilized the relationship among great powers, generating an acceptance of limited hegemony of Russia and Britain.
Rather than cause tension as Russia and Britain vied with each other and with Continental powers diminishing in strength, this acceptance of the new status quo and of methods of communication and arbitration diminished the importance of territorial and balance-of-power thresholds.
After the defeat of Napoleon, British power continued to rise. This evolution can be observed in parallel to the rise of Athens after the coalition to defeat the Persians in 480 BC. The primary aim of both empires was commercial; military agendas were only secondary to this, although to a large extent they were inevitable given the regional discomfort the expanding empires created. For Britain and many Greek states, navies were “an element of the greatest power to those who cultivated them, alike in revenue and in dominion. They were the means by which the islands were reached and reduced…”
Thucydides recognized that navies provided a means of commerce and of subduing reluctant partners. Although Thucydides is frank about Athens’ imperialism, 19th-century Britain was less open about the corollary to its commercialism. Britain saw commerce as an objective good that was its responsibility to establish. Although the use of force was often necessary in the pursuit of this good, Britain did not consider itself a tyrannical imperialist. Foreign Secretary Lord Palmerston desired that “Commerce may go freely forth, leading civilization with one hand and peace with the other, to render mankind happier, wiser, better.”
Sir Percy Anderson noted that “Protectorates, of one sort or another, are the inevitable outcome” of Britain’s commercial objectives.
Britain’s rhetoric revolved around the promotion of peace and the general good; it did not see its military actions as inherently imperialist. The transformation of Britain’s commercialism into imperialism was largely the result of domestic tensions and preferences. The establishment of trading partners and freer trade was a response to a real need for greater resources as population growth outstripped agricultural production in the first half of the 19th century.
Britain sought to generate freer trade within Europe and with America, repealing restrictive trade laws and establishing free-trade agreements. It also established enforced trading systems with China, Japan, and India, conducting extensive military campaigns in the 1830s-40s in both China and India to secure its control of territory and trade. Britain’s negotiations and campaigns in both Europe and Asia can be read in the context of changing relative power as it vied with rivals for commercial advantage and the control of territories. Britain’s actions can also be read as the result of domestic preferences for commerce as a means of jump-starting a flagging economy as well as ideological preferences. While Britain’s behavior is similar to Athens’ as Thucydides describes it, Britain’s was driven by strong domestic economic and ideological preferences, while Thucydides describes Athens’ commercial expansion as a natural progression from weaker to stronger.
The outbreak of World War I was driven by the intensification of balance-of-power and territorial thresholds as well as by a non-rational decision-making process and the breakdown of mechanisms of communication and deliberation. The carefully constructed mechanisms of the Concert of Europe had all but disappeared by the end of the 19th century as powers found that they could engage in expansionary and strength-increasing activities without provoking conflict. These rivalries quickly turned brutal when the remaining thresholds of prestige, ethnic identity, and the balance of power were crossed in the summer of 1914. The outbreak of the Peloponnesian War in 432 BCE, sparked by a conflict among smaller states that drew in allies, is a close parallel to the outbreak of World War I with a shifting balance of power at the rise of naval Britain and the land power Germany. Just as Sthenelais incited Sparta to war, Pericles called for Athens to go to war “resolved against making concessions or consenting to a precarious tenure of our possessions… a firm refusal will make [the Spartans] clearly understand that they must treat us more as equals.”
Pericles calls for a war without the escape route of arbitration or territorial concession to force the question of hegemony. Archidamus, an elder Spartan statesman, appears to be the only voice of reason. “What can justify us in rashly beginning such a struggle?” he asks, warning that Athens has greater capabilities in naval power, and cash funds. “Unless we can either beat them at sea or deprive them of the revenues which feed their navy, we shall meet with little but disaster. Meanwhile our honor will be pledged to keeping on… let us never be elated by the fatal hope of the war being quickly ended by the devastation of their lands.”
Archidamus speaks from a perspective of age and experience; Thucydides notes that the youth and inexperience of many of the leaders of the states led them into the trap of “longing for war from experience or from a belief in its advantage and its safety.”
Likewise, European powers in 1914 were led by men who had not experienced major warfare, and even the highest statesmen were subject to irrational fits of passion: Tsar Nicholas II of Russia wrote to Kaiser Wilhelm II that “an ignoble war has been declared on a weak country. The indignation in Russia, shared fully by me, is enormous.”
It was one thing for generals and politicians to engage in incendiary thought processes; autocrats risked far greater and immediate ramifications. The intensity of conflict over balance of power was certainly greater during this period than it had been in the prior decades, but that in itself was not a tipping point. As in the Peloponnesian War, conflicts created by smaller states sucked in the great powers due to non-rational decision-making. This decision-making process clouded the balance of power and ideological tolerance threshold, causing states to act not in their own best interest.
The events of the 19th century from the Concert of Europe to the outbreak of World War I can act as a focused examination of great power politics and a temporal expansion of the events leading to the Peloponnesian War from 480 to 432 BCE. Thucydides read the balance of power and evolving relative coercive power capabilities as the main cause of war with conflicts among weak allies and non-rational decision-making among great powers the impetus for evolution into a large-scale war. While the balance of power is an important consideration, it is only one of multiple tolerance thresholds that can push states onto the warpath. Thucydides’ simplified argument fails to acknowledge the importance of other kinds of preferences and thresholds, which must be taken into consideration for an accurate reading of international affairs.