The Roman army was unquestionably one of the most effective military forces in history. However, ancient historians disagree over the origin of the army. Plutarch claims that Romulus formed the legionary forces whereas Livy wrote that in early Rome, they fought as a kind of civil militia. Sometime in the 6th century BC, King Servius Tullius introduced wealth classes in Rome. The equites were the highest ranking citizens and formed the cavalry whereas the lowest group were not allowed enter the military.
At this stage, there were 18 centuries of equites, 82 First Class centuries, 20 Second, Third and Fourth Class centuries and 32 Fifth Class centuries. This is how Rome approached warfare at the beginning of the Republic but a humiliating defeat to the Gauls at Allia in 390 BC; when the enemy sacked Rome, led to significant changes in the way the Romans conducted military affairs. Let’s take a look at how Rome’s warfare evolved throughout the centuries.
1 – The Roman Legion in the 4th Century BC
Rather than foolishly continue with the same military outline after their embarrassment against the Gauls, the Romans showed their penchant for innovation that helped it ultimately form one of the world’s great empires. The abandonment of the Greek phalanx was probably the most important change. While the phalanx worked well on open plains, the Romans often fought in tighter spaces, so they needed a more flexible formation.
In the 4th century, the average size of a Roman legion was probably 4,800 men. It consisted of three lines of soldiers. The first line included around 900 hastati that carried the scutum (rectangular shield), a sword and possibly a javelin. Approximately 300 leves were attached to the hastati; these were lightly armed men ideal for skirmishes. The second line included 900 principes; these were experienced fighters with the best equipment in the legion. The third line included 2,700 maniples which consisted of triarii (veterans), rorarii (inexperienced fighters), and accensi (considered the least reliable soldiers).
Regarding tactics, the hastati would attack first, and they had the option of falling back behind the principes and waiting for counter attacking opportunities if they encountered difficulties. The triarii were a few yards behind the second line and would charge with spears if the infantry was pushed back. Their sudden emergence would often surprise enemies and give the infantry a chance to regroup. If a battle was lost, the first and second lines could take cover behind the larger numbers of the triarii and conduct an orderly retreat.
There were some important changes to the equipment too, and Fluvius Camillus is given credit for some of them. Bronze helmets were replaced by an iron headgear with a polished surface so enemy blades would slide off them. Camillus may have introduced the scutum, the famous large rectangular shield, although it was likely the work of several men.
According to Livy, Rome had two legions in 362 BC but doubled in size by 311 BC. These innovations worked well throughout the fourth and three centuries BC as Rome defeated the Samnites, the Gauls and eventually saw off the formidable King Pyrrhus of Epirus; although this was more down to the constantly supply of fresh troops than anything else.
According to Polybius, the Romans had the best army in the Mediterranean by the outbreak of the First Punic War in 264 BC. They had 32,000 soldiers and 1,600 cavalry and could call upon another 30,000 soldiers and 2,000 cavalry from allies. As a result, Rome defeated Carthage but received a terrible shock in the latter part of the third century BC that forced them to evolve once more.