In the ancient world, in Europe, two schools of military thought dominated a certain era of history. One was the phalanx, which was a Hellenistic (Greece, Macedon, Epirus) creation and tool. The other was the Roman legion, which cunningly copied a few of their enemies’ ideas (the Samnite shield and the Iberian sword, for example).
The phalanx involved a number of hoplites dressed in armour and equipped with a spear and a big round shield that protected their body and part of the chap on the left. So, if you were on the right hand side, you had less protection (but more pay for the extra danger).
Spears were of a reasonable length (something like 8’) in most of the Hellenistic world, but when Philip II (father of Alexander the Great) assumed the throne of Macedon he put the army through a revolution of innovation and genius. The spear was lengthened, and named the sarissa (some say 21’, but this might have been an unwieldy size used by Pyrrhic forces. 16’ is also possible. Suffice to say, the sarissa was substantially lengthier than a typical spear). Because the spear was so much longer, it was wielded with both hands, and a kind of gauntlet/shield was bound to the left arm.
Philip also used cavalry to great effect. The phalanx was a powerful force but difficult to manoeuvre because of the length of spear and the fact that its strength lay in a dense formation. So, when the phalanx had an enemy pinned down, the cavalry could assail his flanks and rear and they’d be cut to pieces.
Using his father’s army, Alexander conquered a vast territory, from Albania to Egypt to Afghanistan. All that turned him back was the Macedonian desire to see their families again. Alexander died on the way, and the vast territory lasted only a few years in a united empire.
The legion was fundamentally different, both in arms and tactics. The Romans had a short, sharp stabbing sword, the gladius, and a curved, rectangular shield big enough to protect themselves. They sorted themselves into three ranks, with the principes or hastati (it switched a few times) in the first two ranks and the triarii (veterans) last. The unit of the legion around the time of the Second Punic War was the maniple, of two centuries each. Between the maniples were intervals, through which the rank behind could advance if the rank before grew too tired/bloodied.
Roman cavalry did exist, and was notable for being worse than almost every other branch of cavalry in the world. The legions, lacking a lengthy weapon and a skilled horse contingent, therefore adopted a different approach to the phalanx. The Romans had a blessedly simple idea of warfare. Find the enemy, form ranks, march towards the enemy and then stab everything in the way until it stopped moving.
Its worth remarking that the legions (even when commanded by the mediocre or the outright inept) were very, very resilient. At Cannae, when Hannibal literally slaughtered the Romans, thousands of them actually survived through disciplined and fearless valour.
The problem with comparing the two systems is that they never met on equal terms. I firmly believe that if Alexander had lived and decided to head west, he would’ve crushed Rome. But, he didn’t.
Pyrrhus did head west, but he was capable only of tactical, not strategic, victories. He was a skilled commander (and beat the Romans twice out of three times, although this was partly due to his elephants).
Hannibal beat the Romans many times, but he had a diverse force (briefly including elephants, but also a brilliant contingent of Numidian cavalry as well as Iberians, Gauls and Libyans).
Assessing which was the better system is nigh on impossible, but it’s an interesting question to ask nevertheless. Given the choice, I imagine I’d opt for the legion. The shield’s big enough to protect yourself without relying on a friend, and your weapon is light enough to hold onto when running away (yes, I am filled with heroism).
On an unrelated and sad note, Nicholas Courtney, who played Brigadier Lethbridge-Stewart in Dr Who, has passed away. He starred alongside almost all the Doctors as the head of UNIT. RIP