How did ancient Professional Armies develop?

Figure 1. Stele of Naram-Sin (2254–2218 BC), an Akkadian king, standing over his enemies and who likely employed professional soldiers in his empire as he created a larger empire

Warfare has been a constant throughout human history and conflict can certainly be traced back to our hominid ancestors in our evolutionary past. While technology today is often used as the distinguishing characteristic of warfare, the development of the professional army, that is fulltime soldiers and formations of a standing army, was also an important factor in making warfare an affair conducted throughout the year and allowed the establishment of large-scale states and empires to be possible.[1] This also paved the way for early states and empires to compete more with each other, helping to develop a variety of other social and technical innovations, including shaping our own world.

Early Origins of Professional Armies

In early warfare, from what we can tell when textual sources first become available to us at around the 3rd millennium BC, men would be conscripted for specific campaigns or years when kings were fighting neighboring kingdoms, where the conscripted soldiers would not be required to serve for very long periods and would simply return to their previous employment/professions after the campaign would finish.[2] By the mid 3rd millennium BC, there were attempts to create standing armies of professional soldiers.[3]

Nevertheless, the presence of war helped to solidify the importance of kingship, while also giving kings greater authority in governing and at time economic affairs. The Akkadian army was one of the first empires and its constant state of warfare in the early period of its first king, Sargon, required soldiers to be constantly campaigning rather than fighting on only a temporary basis (Figure 1).[4] This demonstrated the need to create a system of soldiers who could at least be contracted or employed for a period of time longer than the typical agricultural cycle, or rather when their farm labor was not required.

Figure 2. Image of Ramses II on a chariot. Horse-drawn chariots, by the late 2nd millennium BC, became associated with elite troops and royalty.

Another early king we know who attempted to make a professional army was Shulgi (c. 2094-2047 BC), a king who ruled the empire of Ur (the so-called Ur III Empire). [5] While it is not clear what he did exactly, he did make the army more professional, full-time, permanent, and was a force that could easily called upon as needed. This suggests that the army now consisted of soldiers who were strictly employed as professional soldiers rather than having other occupations, although the details of how this was done and the extent of this are not very clear.

In the Late Bronze Age (1600-1200 BC), as empires became larger and increasingly encountered foreign populations, the use of vassal states and the troops they could raise to augment the main army became a new development. This type of development allowed foreigners now to be a part of the army, although their full integration was likely still sometime away, as these foreign units likely served under their own leaders and units.[6] Other developments include the use of elite troops, such as the chariotry by ancient Egypt (Figure 2), as shock troops who were better trained and equipped.

Early development of iron, present in the Hittite Empire, also gave that kingdom an advantage in tools. These differences in equipment and training may have created incentives to provide more resources to at least some of the soldiers of the state, developing a potential officer and professional core that would be complemented with conscripted regulars.[7] These types of early, perhaps semi-professional armies, Egypt and the Hittites, fought each other in a famous battle at Kadesh. In both cases, it is clear that the armies were divided into elite units where supplemented by other, regular units. [8] What was beginning to change in warfare in the Near East and the military, in general, was war not only began to be professional but it also occurred in new and different places. This included the high seas, such as the Mediterranean, where navies developed and specialized troops who were trained to fight on ships developed, perhaps for the first time.[9]

Key Reforms

Figure 3. An Assyrian official meeting with the Assyrian king.

While these early armies may be considered professional and represent transformations in how warfare was conducted with standing armies, it was not until key reforms under the Neo-Assyrian Empire (911-612 BC) do we now see consistent use of professional armies that becomes prominent in the Near East from this period onwards. This begins to spreads to Europe and eventually influence the Roman Empire.[10]

However, what preceded the professionalization of the military was the professionalization of the provincial and administrative system. In other words, running an empire became a more professional task. Beginning in the 9th century BC, we begin to see a new pattern, where kings appear to depend more on trained high officials who are eunuchs and a host of other bureaucratic officials began to be associated with the royal court and provinces. The empire appears to depend on officials, or “Great Ones,” who obtained their position, in part, based on merit and not simply through family or lineage connections to the royal family. [11] Thus, it was the realization that professional administration was needed that likely suggested that other aspects of empire needed to become professional (Figure 3).

In the reign of Tiglath-pileser III (744-727 BC), new military reforms took place within the Neo-Assyrian state that saw a standing professional army develop, similar to what had been done in the third millennium BC, but now with more specialized soldiers along with auxiliary soldiers from various parts of the empire being incorporated into the military. These army units began to have distinct ranks and be part of specialized units within the military (Figure 4).[12]

This included the chariotry, cavalry, and infantry units; specialized units also included naval units consisting of Phoenicians. Other specialized soldiers include engineering units used for siege warfare. In addition, the army’s command structure became more sophisticated with developed ranks, similar to modern militaries. Several different large and independent armies were created within the state, as this helped to ensure that no single military unit would have unrestrained power and threaten the king’s authority. While kings still often led battles, generals now also began to have greater authority to lead armies without the presence of the king. The armies were now always able to fight in any time of the year, giving them a major advantage over enemies who were still constrained by labor shortages during the agriculture season, when men would have been needed to work the fields.

Figure 4. Depiction of Tiglath-pileser III’s professional army fighting and besieging a city with a siege engine.

Although this facilitated the Neo-Assyrian Empire’s ability to conduct warfare and expand in many areas, and sometimes simultaneously, generals could still potentially be threats to the throne. Foreigners were also given opportunities to be involved in the military, which gave them a way to socially rise and benefit from the Neo-Assyrian Empire. Auxiliary and support troops, but also foreign-born officers, began to be evident in the Assyrian state. [13] Furthermore, the Neo-Assyrians maintained the traditional conscription of its citizens as needed, which helped it attain reserve soldiers that were sometimes needed in times of crises or men shortages.

Key to military reforms were reforms to the infrastructure of empire. Rapid transport along long-distance roads, intelligence provided by fast riding horseman and scout teams, and armories provided a way for armies to be mobilized quickly, respond to new and emergent threats where needed, and be properly equipped. Satellite imagery, in fact, shows that these road systems, amazingly still visible, emerged from the great Assyrian capitals and connected to far-away regions.[14]

In essence, the development of the concept of military logistics was also critical for making military forces professionals. Officials and military officers were charged with maintaining this infrastructure and ensuring it can be used for authorized and appropriate purposes. These officials also had a large degree of independence in decision-making, further removing the king from key military decisions. This process contributed to making the military another center of gravity for power in addition to the royal authorities, while also creating more diverse ranks and increasingly larger military bureaucracy.[15]

Later Adoptions

The key development of the Neo-Assyrian Empire now became adopted by later armies, as new states began to realize the advantages of having a full-time army able to march as needed. The Achaemenid Empire (550-330 BC) in particular utilized many innovations by the Neo-Assyrians and even more greatly utilized different ethnic groups into its formations as the empire expanded.[16]

The Roman Empire in the Late Republic and Imperial phases began to also adopt a professional army composed of many units that were able to fight at any given time of year.[17] Initially, both ancient Greece and Rome armies consisted of soldiers that were conscripted for short periods, similar to ancient Mesopotamia; however, this was not sustainable for the Romans as they expanded their realm. The Roman army of the Imperial period heavily relied on volunteers and eventually created a much larger military bureaucracy and system where many legions or units simultaneously existed and composed of many nationalities.

Many more units and specialized roles developed in the Roman army, where non-Romans found the army as one potential way to work up the Roman social ladder. For example, many emperors were of non-Roman origin and had advanced using the military.[18] A key development in this period was basing, on a permanent basis, legions in distant provinces and creating an elaborate system of forts and infrastructure that facilitated the presence of the army for long periods in distant areas. The presence of foreigners within Roman armies may have mitigated the presence of the army in places, helping to make their presence more tolerable.[19] Nevertheless, the key basic structure utilized by the Neo-Assyrians, which made soldiers full-time and developing a true officer core, was largely maintained and was essentially continued by the Romans.


Although the first professional armies were likely founded in the 3rd millennium BC, what we can see is that by the 2nd millennium BC the use of foreigners, elite soldiers, and officers were used within military units. By the 2nd millennium BC, warfare was also happening in increasingly diverse places, including war conducted by navies as they battles to control important sea lanes and trade or communication routes. By the first half of the 1st millennium BC, armies became more consistently professional with full time soldiers and specialized troops. This professionalization facilitated warfare by not making it bound by the agricultural cycles that would have limited when armies could fight.

Another important development was the infrastructural developments that facilitated the movement and equipping armies, including roads and armories. This also enabled far larger empires to now emerge in the Old World, starting first with the Neo-Assyrian Empire and continuing to the Roman and even later empires. The success of creating professional armies, consisting of foreign volunteers and mercenary forces, and having specialized units of officers was first developed by the Assyrians with later states building upon the Neo-Assyrian system. The Roman system perhaps represents an apogee of the developed ancient armies, where armies were now permanently based in distant provinces. However, this system built on the critical foundations laid down from the 3rd to early 1st millennium BC.


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  1. For general information about the history of war and armies, see: Chaliand, Gérard, ed. 1994. The Art of War in World History: From Antiquity to the Nuclear Age. Berkeley: University of California Press.
  2. For information about early conscription in warfare in city-states, see: Trigger, Bruce G. 2007. Understanding Early Civilizations: A Comparative Study. 1. paperback ed. Cambridge: Cambridge Univ. Press.
  3. For information on early professional armies in Mesopotamia, see Bauer, S. Wise. 2007. The History of the Ancient World: From the Earliest Accounts to the Fall of Rome. 1st ed. New York: W.W. Norton, pg. 167.
  4. For information about the Akkadian Empire, starting from Sargon and his likely military developments, see: Spielvogel, Jackson J. 2015. Western Civilization. Ninth edition. Stamford, CT: Cengage Learning, pg. 13.
  5. For information on Shulgi and his reforms, including related to the military, see: Foster, Benjamin R. 2015. The Age of Agade: Inventing Empire in Ancient Mesopotamia. New York, NY: Routledge.
  6. Drews, Robert. 1996. The End of the Bronze Age: Changes in Warfare and the Catastrophe Ca. 1200 BC. New Jersey: Princeton University Press, pg. 151.
  7. Fields, Nic, and Brian Delf. 2006. Bronze Age War Chariots. New Vanguard 119. Oxford ; New York: Osprey.
  8. Meskell, Lynn. 2004. Private Life in New Kingdom Egypt. Princeton, N.J.; Woodstock: Princeton University Press.
  9. Wachsmann, Shelley. 2009. Seagoing Ships and Seamanship in the Bronze Age Levant. 2. print. Ed Rachal Foundation Nautical Archaeology Series. College Station, Tex: Texas A & M Univ. Press.
  10. For information about the Neo-Assyrian state and its development, see: Radner, Karen. 2015. Ancient Assyria: A Very Short Introduction. First edition. Very Short Introductions 424. Oxford, United Kingdom: Oxford University Press.
  11. For more information, see: Karlsson, Mattias. 2016. Relations of Power in Early Neo-Assyrian State Ideology. Studies in Ancient Near Eastern Records, volume 10. Boston: De Gruyter, pg. 38.
  12. For general information on the military reforms of Tigleth-Pileser III, see: Gabriel, Richard A. 2002. The Great Armies of Antiquity. Westport, Conn: Praeger, pg. 127. For other information about Tigleth-Pileser III and his military reforms, see also: Anspacher, Abraham S. 2009. Tiglath Pileser III. Piscataway, NJ: Gorgias Press.
  13. Radner, Karen. 2015. Ancient Assyria: A Very Short Introduction. First edition. Very Short Introductions 424. Oxford, United Kingdom: Oxford University Press, pg. 97.
  14. Altaweel, Mark. 2008. The Imperial Landscape of Ashur: Settlement and Land Use in the Assyrian Heartland. Heidelberger Studien Zum Alten Orient, Bd. 11. Heidelberg: Heidelberger Orientverlag.
  15. For more on the Neo-Assyrian military bureaucracy, see: Albarella, Umberto, and Angela Trentacoste, eds. 2011. Ethnozooarchaeology: The Present and Past of Human-Animal Relationships. Oxford : Oakville, CT: Oxbow Books ; David Brown Book Co, pg. 231.
  16. For a history of the Achaemenid Empire and its armies, see: Sekunda, Nick. 1992. The Persian Army: 560 - 330 BC. Edited by Simon Chew. Elite Series 42. see: pg. 3.
  17. For further details of how the late Republic and Imperial Roman armies functions as a professional fighting force, see: Southern, Pat. 2007. The Roman Army: A Social and Institutional History. Oxford: Oxford Univ. Press.
  18. For information about some of the non-Roman emperors within the Roman Empire, see: Plutarch, Robin Seager, and Rex Warner. 2005. Fall of the Roman Republic. Harmondsworth, Middlesex, England: Penguin Books.
  19. Southern, Pat. 2007. The Roman Army: A Social and Institutional History. Oxford: Oxford Univ. Press.