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, full-time 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.This also paved the way for early states and empires to compete more with each other, helping to develop various other social and technical innovations, including shaping our own world.
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. By the mid 3rd millennium BC, there were attempts to create standing armies of professional soldiers.
Nevertheless, the presence of war helped to solidify the importance of kingship while also giving kings greater authority in governing and, at times, economic affairs. The Akkadian army was one of the first empires. 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). 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.