Our Sea

Part 7 - Roman Armies

Under Alexander the Great, the Macedonian phalanx had defeated armies from Sparta to Iraq. This was a formation of several ranks of heavily armoured men (hoplites) equipped with spears 12 to 21 feet (6.4 m) long, tightly packed into a line. It was was most effective on flat, level ground and, combined with light infantry and cavalry, it enabled the hoplites to defeat to all rival armies.

But, the tightly packed hoplites in the Macedonian phalanx could only fight facing forward. They had difficulty manoeuvring, particularly on rough ground, and this became more difficult in action. Cavalry, bowmen and light infantry helped but this also made control more difficult.

Until the military disaster of 390 BCE, at Allia in northern Italy, when a Gallic tribe sacked Rome, the Roman army was similar to the Greek phalanx, typically consisting of 3,000 infantry and 300 cavalry. 

By the time Romans first fought Greek armies, the Greek system had degenerated. When Philip V, of Macedon, fought a Roman army at the Battle of Cynoscephalae, Thessaly, in 197 BCE, he had no cavalry support for his flanks and was defeated.

The Romans adopted several features the original Greek phalanx but eventually provided the third rank of fighters with standard shields and short spears and swords instead of the long Macedonian spears. 

All men were uniformly equipped, trained and deployed in the distinctive Roman "checkerboard" tactical system with many smaller phalanxes each capable of manoeuvring independently to form, or close gaps in the line, or to extend the line or to move around obstacles. Each soldier was trained to fight off an attack from any quarter and on any terrain and formations were drilled together in a standardized way for an extended period, which permitted even less skilled commanders to manoeuver forces proficiently.

 This open arrangement permitted bowmen and slingers to harass the enemy lines before the main clash and then to retreat through the gaps between the phalanxes. Later Romans soldiers used large shields that could be rested on the ground so each man had more protection and more space to fight. 

 The traditional Greek phalanx of one long line several ranks deep, worked well initially but each line fought its own battle, and as the Greeks became exhausted, the flexible Roman formations permitted a final surge fresh soldiers.

In 282 BCE, the Greek city of Tarentum (modern Taranto), in southern Italy, provoked a war with Rome and begged king Pyrrhus of Epirus (in Northern Greece) for help. He arrived in Italy with an army of 20,000 infantry, 3000 cavalry, 2000 archers, 500 slingers, and 20 war elephants. At the Battle of Heraclea in 280 BCE, he defeated the Romans, but a large number of men died on both sides. The next year, the two armies met in the Battle of Asculum, where Pyrrhus won a second costly victory. The Romans lost 6,000 men and Pyrrhus 3,500 including many officers. Pyrrhus later bemoaned his victory at Asculum, "If we are victorious in one more battle with the Romans, we shall be utterly ruined". (The phrase "Pyrrhic victory" is still in use). 

 Pyrrhus moved his army to Sicily in a campaign against the Carthaginians but, when he returned to Italy, the Romans had rebuilt their army and he found himself greatly outnumbered. After the inconclusive Battle of Beneventum in 275 BCE, Pyrrhus decided to end his campaign in Italy and returned to Epirus.

Prior to the 2nd Punic War, against Hannibal of Carthage (218–201 BCE), the Roman army was a temporary force based entirely on short-term conscription. Rome was able to mobilize 230,000 men in the war against Hannibal who initially led an army of about 50,000 infantry and 9,000 cavalry. Rome's manpower reserves allowed it to absorb enormous losses. Rome lost more than 50,000 men between 218 and 215 BCE, but was still able to field 14 to 25 legions, each of about 5000 men, for the duration of the 17 year conflict.

After the war, a permanent army was essential to fight wars of conquest and to garrison the newly acquired overseas empire. The army had a permanent strength of 150,000 volunteers mostly from the poorest social class who were attracted by the modest military pay. This force was augmented by another 450,000 conscripts plus a large force of non-Italian mercenaries.

The Imperial Roman army (30 BCE to 284 CE) was a professional, standing army of volunteers serving 20-year terms although many served up to 40 years. Conscription of Roman citizens (by this time, most Italian residents) was decreed only in emergencies. 

There were 28 legions during the reign of emperor Augustus from 30 BCE until his death in 14 CE, each with about 5,000 infantrymen for a total of 125,000 men. This increased to a peak of 33 legions of about 5,500 men each by CE 200. There were also about 500 cohorts (regiments) of auxiliary troops each of about 500 men recruited from the non-citizen inhabitants of the empire (about 90 percent of the Empire's population in the 1st century CE). These Auxilia provided cavalry, archers and slingers recruited from Spain, Gaul, Thrace, Anatolia and Syria in addition to heavy infantry equipped in a similar way to legionaries. But, these native units retained their own traditional leadership, organization, armour and weapons.

Under the emperor Diocletian, who ruled from 284 to 305 CE, the Roman army reinstated regular annual conscription of Roman citizens while accepting large numbers of non-citizen volunteers. Citizens and non-citizens served in both the legions and auxilia. The legions, each of about 5000 soldiers (the equivalent of a modern military battalion), were divided into 10 cohorts.

Roman armies succeeded because of superlative logistics and organization, standardized equipment and training, a pragmatic way of copying successful tactics and ideas, strong discipline and ruthless persistence.