Military strength was the backbone of the Roman Republic. Through its soldiers Rome was able to control vast territories, and entire civilizations. From the earliest of times, the Romans realized that training, and battlefield logistics gave them an enormous advantage over their enemies. At first, the army was organized into groups of 100 men called centuries. At this time the army was divided into various classes based largely on personal wealth and rank in Roman society.
This system would gradually change over time. By the 4th century, Emperor Camillus introduced a precise chain of command that made the army more efficient. This system stayed in place during the Punic Wars (264-146 B.C.). During this time period, the army was only kept in field as long as they were needed, and then they were immediately disbanded when they were no longer needed. This was system necessary because the cost of maintaining a huge military was extremely expensive.
However, before long constant warfare caused a lack of stability, and families suffered from economic hardship as there was no one to work the farm or family business. Soon even the upper classes began to rebel, and recruiting which was constant, became increasingly more difficult.
Then in the late 2nd Century emerged the powerful dictator Marius, who became the architect of the most powerful army the world had ever seen. Before the reign of Emperor Marius soldiers came only from the upper classes and they had to be fairly well off to enlist. This was because only the wealthy could afford the expensive armor. Then Marius decided to allow everyone to join and become professional soldiers. They were required to stay for a minimum of 16 years. Next, he organized the soldiers into units called legions. Each legion numbered between 4,000. and 6,000 soldiers, and each legion was divided into ten cohorts. In addition, each cohort was divided in to 6 centuries.
One of the main reasons that the Roman legions were so difficult to defeat was that they were so well trained. The centurions were like drill sergeants, and they each commanded 60 centuries. The centurions emphasized discipline and preparation. Soldiers were drilled and drilled in fighting techniques. Also, they were forced to march long distances in tight formation, with very heavy backpacks. Soldiers ran, swam, and became proficient in all types of weapons. When a battle approached they lined up in a three-line formation. Each soldier was armed with a sword and a spear. Soldier pay was very little, and each soldier was required to provide his own clothes and food. Largely, they ate beans, cheese, bread, and mush. When they reached retirement age they were granted a cash payment and a plot of land. Usually the plot of land was located in recently conquered frontier land where if problems erupted they could be called on to quell any disturbances.
The Roman army used a variety of weapons. Probably, the most effective was the catapult. The catapult, which was called a ballista, hurled rocks, and darts. In addition, the Romans used mobile towers, ramps, and ladders when attacking a city.