The reason you are confused is that scholarship has been confused on this topic for about a century. Woodhouse (1933) described hoplite combat as “in the main, a matter of brawn, of shock of the mass developed instantaneously as a steady thrust with the whole weight of the file behind it—a literal shoving of the enemy off the ground on which he stood.” This provided the image that would set the paradigm for hoplite combat for most of the remainder of the century and become known as the Orthodoxy, othismos as rugby scrum. A decade later Fraser (1942) would write “The Myth of the Phalanx-Scrimmage” with a healthy dose of scorn, something that would become a feature of debate that fell out in two camps of opinion. The debate would simmer until this day, couched in terms of a bellum sacrum between the Orthodoxy and Heretics like Fraser who sought to overturn the notion of literal pushing done in concert by all ranks of hoplites.

These opposing views gathered detail and sucked in a wide range of other topics. If you want to know a scholar’s opinion on diverse topics such as the date when the hoplite phalanx tactics emerge, the amount of formal training or drill hoplites required, the weight of panoply, or the exceptionalism of Greek hoplites, you need only ask how they stand on othismos. For the Orthodoxy, championed by authors like Hanson, Luginbil, and Schwartz, hoplites spring into being by the date Tyrtaios wrote his elegies, or even the poetry of Homer, in a form familiar to Thucydides or Xenophon. Men marched on the field in heavily drilled and disciplined ranks of men with overlapping shields, then charged at the sound of a salpinx, or trumpet, in a simultaneous, running advance of the whole battle line when they came within a couple of hundred meters. They did not stop until they crashed directly into the line of their advancing foes like so many horseless lancers. After one good stab with their long thrusting spears, then crashed, shield on shield and began to push their foes as their own men collided with their backs, supporting their grinding advance. Men were encompassed in their bowl-shaped aspis shields. These has been designed specifically for this moment. When hoplites pushed in a “reverse tug-o-war”, they could shelter their entire upper body within the bowl of the shield and press their left shoulder into their foes with their bodies held perpendicular (as you would when pulling in a tug-o-war). There could be no question of spear fencing outside some possible blind thrusting from rear ranks caught within the masses. One side broke when the other had penetrated its line and caused them to lose their nerve. Then a general chase would ensue, but not to vehement because of the weight of panoply.

Countering this view were an increasing number of authors by the 1980s. Cawkwell, Van Wees, Krentz, Goldsworthy, Holladay, and to some extend Snodgrass, built a competing paradigm over the next few decades. In their view, hoplite combat was a disorganized affair, a “motley crowd” of mixed armored spear men, light troops and cavalry. Men threw spears as often as stabbed with them, and the homogeneous, well trained, hoplite phalanx of the classical authors did not exist until after the Persian wars, if it existed at all. What would become the hoplite panoply developed slowly over the course of centuries, and Tyrtaios would have been more familiar with the tactics used in the tribal struggles of New Guinean warriors than his own descendants of the classical age.

The reason for this schism is simple. Neither side knew what they were talking about. This is not denigration, in fact I applaud them, because they had to veer far outside of the academic training of historians to attempt to find a context upon which to build their paradigms. Reading through the literature you will find countless examples of authors claiming some element of the other side’s argument was physically impossible, or that it could only be done in the manner they describe. It is here that I entered the discussion. I am not a trained historian. My doctorate is in biology, specifically swarm behavior and the way large groups turn randomness into order. I am also a card carrying member of the American Physical Society, so I have a working knowledge of the mechanics and biophysics of humans in combat. I can bring one thing to the debate: context. For example, the Orthodoxy can see no way to have orderly masses of men on battlefields without extensive drilling and training of the men, while the Heretics assume that a heterogeneous mass of troop types must also lack order. But we know how order arises in chaotic groups. You have seen this every time you watch a flock of starlings or a school of fish. Masses of men can be coherent groups in the same fashion.

Like the two camps, you can learn all of my opinions on hoplite combat by my stance on othismos. Othismos is a noun that derives from a verb meaning “to push”. The clearest way to make a noun from a verb is to describe it as “a state when that verb occurs”. Thus othismos is a state where pushing occurs”. This is a crowd, the type of crowd that leads to lethal disasters at sports events and concerts, where people get crushed. The “push” is not really against a foe, but within the crowd between men. Polybios 4.57 for example describes men in othismos as a crowd of routed men try to push through a gate and die in the crush. This is a two component system, a crowd at high density and a shared direction of movement that causes the crush. In the example above and in most crowd disasters the crowd is pushing against walls, but if two shield-walls of men meet in battle, they are the walls upon which the killing crowds form. That is othismos, a situation where men are fighting at high density and crowd on crowd pushing may ensue. It is not a tactic, but an emergent property of large masses of men crowded together with opposing movement directions.

Cawkwell suggested that othismos could have happened late, after a period of fighting. In this he was correct, though he had some mistaken and confused notions about the men fighting in opened order. You gain no advantage by charging for “momentum”, because you can only push when you are packed tight and just 4 ranks of men can stop any number of ranks of men cold as they collide from a charge. Deep ranks are no advantage until the mass pack belly to back. Because of this, there is no reason that hoplites could not stop at the end of their charge and spear fence like any other ancient army would. No front ranker was launched into the spears of his foes. It would have been the front ranks who led the rear ranks into othismos, perhaps as spears broke and they went to the sword. Only at sword range, with your shield pressed to the enemy shield, could your rear rankers pack up close behind you.

Why don’t you get crushed? These are the crowds that regularly kill people through compressional asphyxia. The answer is the aspis, the bowl-shaped hoplite shield. The shield can be held to rest with the upper rim on your collar bone and the front of your shoulder and on your thigh below, arching over and protecting your vulnerable diaphragm from compression. As a scientist, the only way to gain answers to how well this works is through experimentation. I conducted a series of experiments with hoplite reenactors and HEMA practitioners. Pushing in files of six ranks we generated 368 kg (3600N) of force. More importantly, we could sustain almost 200kg just by leaning forward into the other group. I will not list the authors who said this could not be done, but suffice to say it can. We also showed why 12 ranks of Spartans could hold off 50 ranks of Thebans. As you add more men to the files, you get less benefit from each new man. By the time you are over around 16 ranks, you are adding very little force, as the men in front absorb they input due to imperfect packing.

So in my, let’s call it “Reconstructionist” scheme, men are free to enter battle throwing spears or fighting for an extended period of time, often one side would rout before the battle moved to a crowded state. But if it did become a matter of tight packed ranks, the posture that keeps your shield in place to protect your diaphragm from compression also allows your right arm to remain free to use your sword or spear. This was othismos. As Xenophon may have described it: fighting, pushing, dying.