by: Will Thomas
The cohorts made up the main fighting line.
The light troops supported the main line if they needed to fall back.
The cavalry protected the flanks and could move forward to flank the enemy.
The reserves helped defend the flanks and support the main line.
The tortoise formation was used to defend against incoming missiles.
The wedge formation was used by attacking legionaries and useful for breaking into the enemy line.
When the line advanced it pushed the enemy into restricting positions in which the Celtic long swords weren't useful but the Roman gladius(short sword) was useful.
The skirmishing formation was the opposite of the more tightly packed ranks of a normal formation.
This allowed for much more mobility.
The repel cavalry was used, as the name implies, against attacking cavalry.
The front line would kneel down and form a firm wall with their shields so only their spears were protruding.
No horse, no matter how well trained, could be brought to break into this barrier.
The second line would be waiting with spears, ready to throw them at the enemy when their horses stopped.