Men Joined the Roman Legion for Booty
Part of the reason why the poor were so eager to sign up for the legion was the chance of collecting booty. The Romans were known for being particularly brutal when they invaded a city. They would start by killing every living thing they came across, killing all the people and animals of the town. Some suggest that this might have been a form of intimidation for anyone that saw the village afterward would see nothing but corpses and dismembered animals. Once the order was given to stop the massacre, the looting would begin.
Half the force would be allowed to loot the town freely while the other half stood guard or carried out other duties. The men would be allowed to loot the corpses, the buildings and even the art, anything of value was free to take. Once all the booty was collected it would be gathered together and then divided between the different legions that had been on the attack. Then the loot divided among the legions is divided among the individuals within each legion. It was divided among everyone, even those who were not part of the orders to loot the city. This meant that everyone had a chance to get some of the spoils of war. This effective method of insuring that everyone got their share was how the Roman legion kept down dissension in the ranks. When every man knew that they would get their share they would not have a reason to disobey orders or feel like they were not treated as important as other men in the legion.