The 2nd century brought more refinements to the Roman Army, where the Roman Army comes to be known as the common Roman Legion. The formations changed, the armor changed, and the weapons changed. The numbers of the Roman Army also increased incredibly. This is also the time period of great reform and corruption among the leaders of Rome. But the army always comes out stronger.
In the formation of the legions, the hastati were still the front-bearers in the line. The principes and the triarri also stayed in the same sequence, but the rorarii and accensii were done away with. But a new type of soldier arrived in the velites. The velites were actually in front of the hastati and were more mobile in their attacks. They would serve as a good offensive in striking the enemy with their javelins, then they would stop fighting and fall behind the rest of the army.
The legions contained 3 subdivisions that had each ten maniples. Each maniple was under the command of two centurions, one for the left and one for the right. These centurions led a whole lot more men than ever before, because of the following figures within one legion:
10 hastati maniples = 1,200 soldiers (120 men for a maniple).
10 groups of velites = 400 soldiers (40 men for a group along side the hastati).
10 principes maniples = 1,600 soldiers (160 men for a maniple).
10 triarri maniples = 1,600 soldiers
10 groups of cavalry = 300 cavalry
Total number of soldiers = 5,100 soldiers
The new armament worn by the soldiers was to their benefit as well. The hastati wore bronze breastplates, or if they were wealthy, they would wear chain mail. They also wore purple and black feather plumes on their helmets which were made of bronze once again. In the past, the Roman Army originally was using bronze helmets, then changed to iron, now they're back to the bronze helmets with more thickness to the helmet. These feather plumes were 18 inches high to make the soldiers look more intimidating to the enemy.
The weapons also changed for the soldiers. The hastati carried a pilum, which is a wooden spear with an iron tip. The hastati carried short javelins, about 4 feet in length, but they had a nine inch head, good for killing. The javelins were also constructed that once they hit something, they would bend and the enemy could not use Rome's weapons against them. Then the other ranks of the legion carried a long spear called the hasta. And every soldier carried a gladius, which is also called 'the Spanish sword', because, obviously of its origin.
It was also in the 2nd century, that commercial enterprise was becoming more and more popular among Roman citizens. This meant that making a selective service into the army would have been just ignorance on the part of the Roman government. The effect on the Roman Army was then that they would not have a steady stream of men filtering through the Roman Army. And thus it was becoming very hard for Rome to maintain order within its territory. This led to changes of six-year continuous service for enlisted men. This also led to an increased use of allied forces. In one instance, two-thirds of a force of men controlled by the Roman Army was allied troops, much more than actual Romans. But all in all the situation became more and more political in a social war, that was fought for a little while, then came the reign of the Caesars.