Introduction

The current dynamics of the conflicts involves a variety of actors, who in the past did not have the same importance in the origin, development and outcome of them. From the neorealist perspective of international relations, the international system is state-centric and any actor different from the state only has a peripheral relevance, so that the political actions performed by him, especially the war as an instrument to ensure national interests, would have a custodial or exclusive character and no other entity would be able to rival its power. That is to say, that the state maintains its ability to confront other states or respond to security threats, from terrorist organizations or separatist groups, for example.

In terms of the conventional or interstate war, which could also be called traditional, the state can face their opponents by itself or through alliances with other states. But the emergence of revolutionary / counterrevolutionary war, from the nineteenth century, demanded that the colonial powers consider new ways to prevail in war, being exposed to the siege of non-state groups, which were pursuing independence or secession with fighting methods and organizational structures that they were not used to, and that put into question the usefulness of their hierarchies, strategies and tactics.

It is all about a parallel context to the continuity of the confrontations of interstate character, with the preeminence of those ones in the first half of the twentieth century, but which becomes more common after the Cold War (^{Peñas, 1997}), when the bipolarity of the international system generates an indirect confrontation between the United States and the Soviet Union, with the support of each towards governments and armed groups that are favorable to their strategic interests in Latin America, Africa, Middle East and Southeast Asia. Thus, the logic of war underwent a change with the interaction between state and non-state actors, finding, in any case, their starting point in scenarios such as the Spanish Civil War of 1936, between republicans and nationalists and which ended with the victory of the latter, and the Popular War promoted by Mao Tse-Tung in China, in 1949. Both wars have served as a paradigm for the formation of Latin American communist guerrillas, as well as organizations such as the African National Congress in South Africa or the Organization for the Liberation of Palestine.

However, the environment of the post-Cold War has a higher complexity and Mary ^{Kaldor's approaches (2001)} transcend the dichotomy of conventional warfare and revolutionary / counterrevolutionary war, to move towards a distinction between old and new wars, according to elements like the political objectives of the actors, their methods of struggle, means or sources of funding and organizational structure. In Kaldor's perspective, the idea of the State having a limited power to face the challenges proposed by actors such as the terrorist groups, the international networks of the organized crime or phenomena like piracy and the growing role of the mercenaries, either individually or linked to military companies of private security (^{Mayer, 2009}). With this diversity of actors, the notion of distribution of power in the international system (^{Waltz, 1979}) becomes important, because it becomes useful to explain a reality that is difficult to question: that power is diffused among a multiplicity of entities and the state monopoly of legitimate violence is not so obvious, so that the state's capacity to resolve internal or international conflicts is conditioned by the actions of other actors.

In this context, the mercenary seems to be a key subject in the development of most of the violent conflicts, including prevention and even the balance of forces of those who face each other. In this regard, the levels of conflict of Heidelberg Institute for International Conflict Research (HIIK, its acronym in German) are useful to understand the time when the mercenary military or private security company enters the scene. This institution distinguishes between non-violent and violent conflicts, to establish five levels of intensity: levels of dispute and nonviolent crisis are assigned to the non-violent actors, and levels of violent crisis, limited war and war violent correspond to the violent ones (Conflict Barometer, 2013). It is worth noting that the armed actors, especially the mercenaries, are characteristic of violent conflicts and their three levels of intensity.

This work is aimed at explaining the objective importance of mercenaries in international conflicts, highlighting the advantages, risks and consequences of their actions. In addition, it intends to state that they are not new actors in the war, and rather that they have participated in it since ancient times, and for such effect, a comparison between the mercenaries of classical Greece (sixth to fourth centuries BC) and today's, an exercise that will help us understand its evolution through 2500 years of history.

Greek Mercenaries

One of the top works of literature and classical Greek history, The Anabasis of Cyrus (also known as The Persian Expedition or The Expedition of the 10,000), of the military historian Xenophon, recounts an episode from the late V century BC, in which, Cyrus the Young, governor of the satrapy of Minor Asia, plans to dethrone his brother Artaxerxes II, king of Persia. To achieve this, he recruited an army that included 13,000 Greek mercenaries (the figure varies, depending on their being Greek or Persian sources, from 10,000 to 13,000, and is known as myriad, or myriás, which was the unit of measure of the Persian armies, or myríoi, expression used by Xenophon to refer to an innumerable or large army), with whom he undertook the expedition from the east coast of the Aegean Sea into Persia. In this story, most of the army flees in disarray before its defeat in the famous Battle of Cunaxa, near Babylon, while 13,000 Greek soldiers remain united in the fight, under the command of Clearco, Spartan commander. Being defeated, they must negotiate with the enemy and Greek commanders are beheaded, so the mercenaries elect the Athenian Xenophon as the new commander, who guides on the journey back to Greece.

The Greeks did not know the term mercenary and the environment in which these were developing was very different from today. First, the city-state forged particular social, economic and political relations, where the mercenaries we know today would have little or no space, while those of that time occupied an important place in social life, acting, for example as mediators in relations between the aristocracy and the rulers of the Mediterranean in classical Greece, and not only as combatants. The people who took part in the discussion of public affairs in the Assembly (Ekklesia), were generally the same ones going to war on behalf of their cities, and they are well documented by Thucydides, in the History of the Peloponnesian War and Herodotus, in history. Thus, the war was a central issue in public life and was a civic obligation to fight for the Polis, so that citizenship was honored in war (^{Marinovic, 1988}), establishing then an identity between citizen and soldier, for they were the same person, as when they speak of the peasant as a soldier and the soldier as a peasant, defining the Greek citizen as a soldier owner of a piece of land, who went to war to defend three things: his city, land and freedom (the symbiotic relationship between private property and the idea of freedom come from Greece), bringing his own weapons and resources.

Greek or hoplite soldier (hoplites) had a strong sense of community, and the hoplite infantry was structured around the idea of mutual protection (each soldier protecting himself and watched over his partner), and this is why the war was of a political nature for the Greek citizen: if the war was not assumed, the community and the ties that had been built around it could disappear. The links, as the one between parents and children, or the independent farmer and his land, they articulated in turn the relationship between war and political life of the community, a union that began to break with the appearance of mercenaries, expert and more professional soldiers, who dedicated exclusively to military matters and whose skills surpassed those of the traditional hoplites (^{Marinovic, 1988}). Undoubtedly, the relationship among war, socio-economic structure and the politics of Greece changed dramatically with the increasing incorporation of mercenaries into the armies, since a new division of labor made the peasant lose his independence to the extent of his renouncing his politic responsibilities renounced their policies to entrust the protection of his home and his State to a warfare specialist.

From the reforms implemented by Solon, with its 594 BC Constitution, Athenian society was ordered according to the role that each individual played within the state and in the conduct of the war as well as in regards to his ability to provide the necessary weapons for military service (^{Trundle, 2004}). Thus, there were three recognized strata: the richest citizens formed the cavalry (hippeis); smallholders and traders formed the infantry (hoplitai), and the poor farmers or land workers (zeugitai), neither went to war nor had civil and political rights. With the introduction of mercenaries, economic relations in Greece experienced a change by virtue of the compensation that they received in exchange for their service to the polis as warriors, i.e., a new type of social relationship was established, by assuming the participation in the war as a job for which the citystate hired a specialist. It is clear, then, that the mercenary represented a major social, economic and political phenomenon for the life of classical Greece. So much, that they began to form independent military communities outside the polis, where individuals shared a task, a series of economic aspirations and growing significance, determined by the needs and strategic objectives of the city-state in war.

According to Trundle,

Cyrus's experiences and his Greek mercenaries provided a paradigm for future events. Between 399 and 330 B.C., there were many attempts from the satraps to get independence from the Great King. The collapse of the unity of the Persian Empire led to the prolific use of Greek mercenaries to help maintain the imperial authority, or to prevent it from collapsing. The military campaigns were becoming more frequent and peasants found it difficult to leave their land to go fight in the war, so the appearance of specialist soldiers, such as archers, launchers and light troops, capable of conducting complex maneuvers and use special weapons, forced states to hire trained professionals who would ensure more accurate results on the battlefield. (2004, p. 7).

The fourth century B.C. opened new ways to specialization and professionalization of the war, and favored great opportunities for mercenaries, who knew that in each region there would be work for them, and at different times of the year. This epoch, besides the great war events that characterize it, has been called by some historians as the Great Greek mercenary explosion of the fourth century (^{Miller, 1984}).

There are some terms that can be associated with the category of mercenary in classical times, in the absence of a specific name to refer to it. (^{Trundle, 2004}). Among the most known and used by Greek historians and military strategists, the Epikouros stands out, which would mean parallel fighter or assistant, to refer to the who fights alongside the regular soldier or Stratiotes. Second, Xenos, which refers generically to the foreigner, and applied to the V century's wars would explain the foreign-born fighter. Later, towards the end of the V century B.C. and throughout the fourth century. B.C., the xenos began to be called misthophoros, or employee, referring to the soldier who receives a salary, and this was the most common term used by Greek historians of the period of the Classic Rome. The Employee status seems to be marked by a pejorative connotation, because receiving a financial compensation in exchange for a service contravened aristocratic values. Moreover, working meant a way to give up freedom (eleutheria) and independence (autarcheia) for the aristocrats, so the speakers, when seeking to discredit or denigrate their opponents, would use words related to a salary or contract.

However, the Athenian, Spartan aristocracy and, in general, of all the Hellenic world, was aware of the historical moment that the region lived and that the economic, political and military power would allow them to project both the Ionian and the Aegean Sea, to form coalitions which then would lead to the building of empires (^{Miller, 1984}). In the case of the Athenian Empire, the commercial and territorial positioning during the Persian Wars, demanded superior military capabilities to those required to defend the polis, and Athens was willing, as indeed it was proved, to invest huge amounts of resources to consolidate its power against Persia, and mercenaries acted as an effective instrument to achieve that goal, because they were abundant in the region and their level of expertise before the conventional hoplite infantry was their greatest quality. Then the Greek aristocracy was prey of a political contradiction, by rejecting the figure of the mercenary in the areas of public deliberation of the polis, but admitting its need to determine better results in foreign wars.

The Organizational structure of the Greek mercenary armies

In the analysis of the forms of organization of the groups and their structure, the criteria applied nowadays to the context of the new wars can be adapted to better understanding of the mercenary phenomenon in classical times, the relationships woven between mercenary soldiers and their employers, as well as the hierarchies established within the mercenary armies. Considering this, the notions of form or organizational chart, organizational and operational elements, and global scope (^{Cragin, Daly, 2004}), fit in the mercenary dynamics of the V century B.C. and firstly, it can be assumed that the relations between the mercenary and his employer were basically economic, of payment, although there were other relevant factors to determining the position of each one in the battlefield.

The employer (misthodotes), responsible for recruiting and hiring mercenaries, was, likewise, the one who paid the wages and in many cases acted as a commander of the units. In short, he was the hierarchical superior of the mercenary and to whom he should pay service and obedience. However, the employer was not always independent and was subject to the decisions of rulers of the poleiso of Persian satraps, i.e., he had an intermediate position of power between the mercenary and the political leader, either in the Persian Empire or in any Greek city -State.

Often, the Persian kings commissioned generals, princes or ambassadors the formation of mercenary armies from Greek troops, and a relationship in which the employer had his own army, composed of native or local forces was established, and it was complemented with «barbarían troops» (term used by the Persians to refer to the Greek mercenary troops), and led by Greek generals or strategoi (^{Trundle, 2004}), whose presence in the battlefield led to friction, due to the power conflicts that those ones had with the employers, for not possessing autonomy to command operations and be subject to their orders. As Trundle says,

The generals or strategoi were used by the kings or princes to lead campaigns, rather than play any diplomatic or mediation task between cities. They were in charge of commanding operations in the battlefield, and to mediate relations between the employer and junior officers or first line privates. A general could be both a noted character in the life of the polis, and a simple man with the ability to raise a small mercenary army for any campaign. His status was not well defined, for it was not a necessary condition to occupy a prominent position in the polis (2004, p. 134).

Apart from the organizational structure, the consideration about the national identity of mercenaries or their loyalty to the poleis they came from is important for the comparison that has been proposed with contemporary mercenaries. The multiplicity of city-states scattered along the shores of the Aegean and the Ionian Sea, forged less strong identities than the modern ones, boosted by the nation- State. The absence of a national Greek identity, because of the constant rivalries among poleis competing for a space in power in each island or mainland, facilitated the mobility of mercenaries, who did not feel constrained by emotional ties with their homeland. In fact, the first attempts of Greek unity came in the form of federations or leagues, as the Delian League, the Peloponnesian League or Aegean League, but they were organized more around pragmatic and strategic objectives than for sympathy or common values, and the most paradigmatic example is the recognized General Peace of the fourth century, or Koine Eirene, among Sparta, Athens and other city-states.

The 21st century mercenaries: the controversial figure of the security contractor

As it was explained at the beginning, the evolution of the violent conflicts have been marked by the appearance, in every epoch, of new actors who pursue different political, economic, social or religious objectives, as well as the interactions that occur among them. And the mercenaries, as demonstrated in the first part, have played a central role in conflicts from classical times. Establishing the importance of mercenaries in the international conflicts today, has led various authors to reassess the idea that they constitute a novelty in the context of organized violence of post-Cold War (^{Kaldor, 2001}), since if there is evidence of its historical continuity, any discussion on that matter should focus on the transformation of the phenomenon over a period of 2,500 years. At the same time, that evidence provides elements to differentiate the environment of the military confrontation in the Greek international stage of the sixth to fourth centuries B.C., from the characteristics of today's conflicts, dissipating any attempt to reduce the reality of the mercenary to a case of violence privatization.

In his distinction between old and new wars, Mary Kaldor speaks of general guidelines for their development, and notices a change in the type of violent conflicts that recur in every region of the world: the proliferation of interstate conflicts until the end of the Cold War, moving towards the abundance of internal or intrastate conflicts with a regional or international impact, which occur in the concert of globalization and in weakening situations of the nation state, along with the erosion of the monopoly of state legitimate violence and increasing difficulty of the states to face new threats to their stability. These would be suitable circumstances for the emergence of jihadist groups or separatists, drug cartels and human trafficking, in the same way they would be useful to explain the growing need of the states to resort to the services of the PMCs (private military companies), which would be the contemporary version of the mercenary armies (^{Moesgaard, 2013}).

That point of view favors a possible relation between the weakness of the state and the presence of mercenaries in conflicts that the first one with its power has neither got to prevent nor resolve. But the reality of these actors gives an account of the greater complexity, since its performance, although oriented to unstable societies and, therefore, unable to contain the violent competition among groups for the territory, resources or political power, has been conceived by strong and organized states, with political, economic and social stability, holders of a recognized ability to project their national interests. In other words, groups of mercenaries may arise as a result of the state weakness to deal with the problem of widespread violence, but this is not the only condition on which their existence depends (^{Mayer, 2009}).

Unlike the limited role that the Greek, Roman and Persian mercenaries preformed as warriors, strategists or mediators, the scope of the current mercenary enjoys a great extent, and their tasks can range from intervention in crisis situations, to consulting and security advice for private companies. Under these conditions, the mercenary has a versatile feature, adaptable to spaces that do not always involve armed confrontation, although it remains the main source of work. And for that reason, today's mercenary can also be called security contractor, which does not mean that all private security provider can be considered a mercenary.