Adam Elkus has a lengthy and meaty post at Abu Muqawama, inspired by General Mattis, one that you should really read in full:

The Mattis Book Club

….But while gaining an understanding of the nature of war is useful, there are a lot of things it won’t do. This becomes most apparent in the section of the email where Mattis makes specific claims. Mattis repeatedly states that nothing is new under the sun, makes comparisons across big temporal zones (Alexander the Great in Persian Iraq vs. 2004 iraq), and advances specific analytical arguments about military theories. He does so on the basis of a sweeping generalization that 5,000 years of warfare tells us in aggregate that war has not changed. While this makes for a rousing line, it is also a fairly problematic statement. How do we really know that the nature of war has not changed in 5,000 years?

We should recognize that this is an isolated quote, and strive to not take out of context what was a heartfelt letter to a colleague in need of guidance. But the argument itself—as the cumulative product of a process of self-education in the nature of warfare, does merit some critical analysis. It is part of a humanistic conception of war that stresses the unity of military experience across the ages, and puts the fighting man’s will first. What Mattis dashed off in an email has been repeated by others in journal articles, blog posts, essays, and books. The military historian Brian McAllister Linn, in his seminal study of the Army’s cultures, dubbed it the “heroic” style of war. Linn constrasts this humanistic style this with technocratic Managers, defensive Guardians, and other military tribes with differing values and approaches.

So what do we know about 5,000 years of constant violence?

Often times the answer is that it depends. As my Fuller and Liddell-Hart examples illustrate, the quality of historical accounts is extremely uneven. Military history as a modern discipline only started with Hans Delbruck, a civilian who did some basic math and discovered that many of the most prominent chroniclers of pre-modern warfare were flat-out wrong about ancient history’s greatest battles and campaigns. Anthropologists still argue today about the nature of violence in the evolutionary state of nature and whether it can be mapped to violence in settled states. Second, it may be true that war is war in the Clausewitzian sense. But while it is technically true that Alexander’s Iraqi opponents and Sadrist mobs are both humans seeking to use force to impose their will, this in and of itself is not very useful. There are fairly prominent shifts in the character of politics, the international system, techology, wealth, and society that matter too.  

What constitutes politics is a very important point.

Take for example, the Romans. There was a definite shift between the Early-Middle Republican eras and the Late Republic in elite politics and the socioeconomic conditions upon which Roman assumptions about war and the organization and supply of Legions rested.  Growing inequality of wealth was making it harder for Plebian citizens to afford to muster for a campaign, the need for longserving “professional” Legates to maintain “institutional memory” of the “arts of war” of the Legions expanded even as the highly coveted opportunities for Patricians to command decreased. These trends clashed with what the Romans liked to  believe about themselves and the friction between advocates of reforms (often necessary and practical) and the upholders of  centuries of honored tradition made Roman politics increasingly bitter, dysfunctional and subsequently lethal. The early Romans would have been horrified by Marius and Sulla, to say nothing of Antony and Octavian.

In the end, the politics of the Romans, along with their battlefield experiences, changed how they organized and manned their Legions, why and how they fought the wars as they did and continued to shape Roman warfare as long as the empire lasted. Julius Caesar would have been as startled by Late Antiquity’s semi-barbarian “Roman” Magister Militiums as his own career would have dismayed Decius Mus.

Adam goes on to have some useful things to say about the need for combining historical and quantitative  social science  methodologies and the limitations of each. Delbruck’s overstated skepticism of the ancients aside, sometimes we moderns do not count any better in war or politics – or at times,  even worse