On the left side of the soldier's body was his trusty shield (scutum) This was unusual in design since it was not flat, as was the case with shields used by Celtic tribes, but semi-circular.

Construction
To make the scutum light enough to carry when marching, it was builds mainly from flat strips of wood that were laid at right angles to each other. Much in the same way that plywood is made today.

The scutum was sealed together then heated and placed in a press while still hot. This press would give the distincive rounded shape. It was then allowed to cool naturally, then when it was removed from the press the scutum would retain it's shape.

It was shaped was designed in this way so that any missiles thrown at the soldier would be deflected to one side. This would mean less effort by the soldier would be needed to defend himself. If the scutum was flat, a rock hitting the scutum would make a direct impact, which meant the soldier's arms would have to absord the power generated by the missile. Being curved, the scutum would send the missile off to one side, so there would be less effort needed to deflect the energy transmitted to the soldier's body.

The scutum was not only a defensive tool, it was a weapon in it's own right. The central rasied portion in the middle (umbo) was forged from one piece iron or bronze and was not only used as protectiion for the left hand, but also as a weapon. The raised boss would be thrust into the enemy's face or chest, causing severe inhury and disabling them. Then the sword (gladius) was thrust forward into the opponent's body.

Using the scutum in battle
Up to 500 soldiers would be deployed in a line, shoulder to shoulder facing the enemy. The shield (scutum) is held slightly away from the body so the soldier can move it up and down to block incoming missiles	They would wait for the enemy to come close, then as one they would take a step forward and thrust their scuta into the bodies of faces of the enemy, causing them to lose balance and so randier them vulnerable.	The scutum is then withdrawn and the sword (gladius) is thrust into the body of the opponent. Note the way in which the gladius is deployed horizontally to pass between the enemy's ribs into his vital organs.
The legionaries would advance in a line towards the enemy thrusting scutum, then gladius. It was this action, scutum, gladius, scutum, gladius that would disorientate the enemy and take their front warriors out of the battle.