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 phalanx's 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 Magnesia, or for the phalanx to lose its cohesion due to prolonged movement forward or advancement through unfavorable terrain, as at Pydna. Yet, regardless of the many Roman victories against the Hellenistic Kingdoms, the legion never won against a phalanx by frontal assault. Even at Pydna, it took the strange withdrawal of the Macedonian cavalry for the Romans to finally outflank the phalanx and claim a bloody victory.