The Roman army was one of the best in history, they created a massive empire all over Europe, North Africa and Asia Minor. They were brilliant tactically. If they were getting charged at, they would break into two lines; the front line would throw their spears, which were built to snap in half on impact to stop enemies throwing them back, then the second line would throw their spears while being protected by the front line. They also all carried a short sword. Unlike most armies they wore their swords on the right instead of the left-hand side. This meant instead of drawing their swords across the body they were pulled out ready to jab at the enemy.
One of the Romans most famous formations was the Tortoise or Turtle; this was where they marched in a rectangular formation. The people at the front would hold their shields, which were rectangular, in front of them where as the people at the side would hold their shields to the side which was open to attack. The soldiers in the middle of the rectangle would hold their shields over their heads, creating a box with all the men inside. This was a very strong, tight formation and the soldiers could, if they had been invented by then, hold a bulldozer up on top of them. They could march up to a fort in that formation and not one of them would get hurt. The defenders, rather than using ranged weapons, would have to charge them. The Romans, even though it was not the best form of attack, could jab their swords out of the box while being protected by their shields.
The Roman army was the most disciplined in fighting and in preparing for war. The higher the rank, the more work they did. For example, if they were setting up camp they would first dig a trench around the perimeter then put stakes on the inner circle. The best and most established soldiers would do the digging and putting stakes up while the less experienced soldiers would put up the canvas for tents and make fires etc.