Even More Roman Formations

The order to repel cavalry brought about this next formation. The first rank would form a firm wall with their shields, with only their pila protruding, forming a line of spearheads. A horse, no matter how well trained, could not be brought to break through such a barrier. The second rank would then use their spears to drive off any horses that came to a halt near them.
The orb is a defensive position in the shape of a circle taken by a unit in desperate straits. It provided for a reasonably effective defense, but needed a very high level of discipline by the individual soldiers.

"Roman Army Tactics." The Roman Empire. Web. 23 Mar. 2010. http://www.roman-empire.net/army/tactics.html.
Repel Cavalry! Digital image. Roman-Empire.net. Web. 2 Apr. 2010. http://www.roman-empire.net/army/repel-cavalry.html.