The idea that Egypt was unified through warfare between the Upper and Lower Egyptians seems be the dominant modern understanding of Egyptian Unification. The evidence of warfare seems to be lacking in the archeological record though. It seems like most of the evidence of warfare comes from artifacts such as the Narmer Palette that have multiple interpretations. It is admitted though, in Chapter 5 The Rise of Complex Society and Early Civilization, that a debate exists about whether the Narmer Palette even represents an actual historical event. Other than the palette though, and other artifacts, mentioned but not discussed, in the chapter, there is little evidence to support the idea that warfare was the unifying force in predynastic Egypt. According to Chapter 5, “sites in the Delta with destruction layers are lacking” (pg 107). If warfare were truly responsible as a unifying force between the south and the north, there would be archeological evidence to support this idea. Excavations would reveal evidence of conflict, which could come in many forms, such as burnt houses, burials with evidence of scavenger activity (suggesting remains left exposed for a period of time), tools of warfare i.e. weapons, as well as defensive tools such as fortifications. This evidence is either not talked about in the chapter or not present in the excavations, suggesting that while warfare may have been present in predynastic times, it might not have had as strong an influence on Egyptian unification as some suggest
I think the issue of how unification actually occurred, or at least could have occurred, is explained more thoroughly in the chapter of Egyptian Archeology by Kohler, Chapter 3: Theories of State Formation. Kohler explains state formation and the processes involved in a broader context than mere violent conquest. Even if warfare was the origin of southern control over the north of egypt, processes of state formation were still essential for creating a unified culture that persisted for thousands of years. The important aspects of state formation that Kohler focuses on include, specialization in crafts, trade over long distances, social complexity, centralization and a state ideology (pg 38). All of these processes can be seen in the archeological record though. Craft specialization can be seen in the pottery assemblage as well as the “fishtail and rhomboidal flint knives [that] were manufactured by highly skilled flint knappers” (pg 39). Trade can be seen in the presence of copper from Palestine as well as gold and other resources from outside the Nile Valley. Social complexity and state ideology can both be demonstrated in the mortuary record, as well as centralization to some extent. Centralization is also indicated by the trade networks (pg 41) as well as the larger organization of the state. While state formation can clearly be demonstrated it is much more likely that it occurred through the processes discussed in Kohler, rather than as the result of warfare. Kohler’s processes can and have been found in the archeological record, and while warfare should (at least if it occurred) be present in the archeological record, this is not the case.
Warfare may have led to unification of upper and lower Egypt, but if it did, it seems like there would be more evidence. Warfare may be a common explanation for unification, but it doesn’t explain the larger processes necessary to form a state that could last for thousands of years. Warfare destroys rather than creates which is why it is interesting to see an explanation of state formation that shows the true complexity of forming a state. To some extent it might be that warfare as a form of chaos, was what the unification was opposed to, unification being seen as, along with the ruler, a representation of order.