Even thought the Roman army had unequaled numbers, the safety of its ranks was a very serious issue. No chances were taken when a legion would travel. Before a legion could stop to rest for a day a camp had to have been built. These camps were not just tents in a field, they were fortified areas made specifically in case of a sneak attack. As soon as the legion would stop, specified soldiers would begin digging a trench around the camp's perimeter. The camps were usually square or rectangular. This trench is a integral part of the Roman fort. It gave the camp automatic high ground against any siege force. On the inside of the trench a pike wall would be erected. It would make the trench doubly effective and protect the camp from projectile attacks. If the legion was to stay put for more than a night, towers would be built at the corners of the camp. The towers would serve as lookout posts and support for heavy artillery and/or archers or spear-throwers. The inside of the camp was carefully arranged to a set plan created by Rome. At one side of the camp there were the Centurions and officers bunks, and a meeting place used for briefings and speeches by the commanding officer. The other side of the camp would be full of the soldiers bunks. Hundreds and hundreds of these tents were stuffed together in this part of the camp. Dividing the two sides was an avenue for any passing legion to go through.
These camps would take hours to set up, but would often mean the difference between surviving the night and a massacre. Whether it be propaganda or not, soldier would be given messages warning about legions attacked and hurt badly (never defeated, of course) because of a lack of protection while resting or sleeping. Fear was a great motivator for the Roman soldiers.
Often these camps created while on the move would be adapted later to permanent camps or full-scale forts. in fact these camps were so well built that, once abandoned, they would be adapted by the locals as a seed for a city.