 Complete the following phrase:  The primary drawback of the phalanx was its vulnerability to attacks from the rear and flanks. This is the reason why it depended on the units on its flanks to at least hold off the enemy until he would naturally break from the phalanxs irresistible pressure. It also had a tendency to fracture, when led across broken terrain for extended periods of time in close ordered battle formation. The Romans would later be able to use this weakness against the phalanx as their more mobile maniples could withstand the pressure of the phalanx longer than more traditional formations, thus earning valuable time for their wings to outflank it, as at Cynoscephalae and 