The attack on Robert is significant because it symbolizes the breakdown of order and civility that occurs when people are placed in extreme situations. Without the guiding influence of adults, the boys are quickly overcome by their animalistic instincts and engage in savage behavior. The attack on Robert is a warning about the dangers of mob mentality and the ease with which people can be manipulated and turned against each other.
The attack on Robert also underscores the importance of leadership and the role that strong leaders play in maintaining order and stability in society. Without a strong leader, the boys are quickly divided into factions and become a threat to each other. The attack on Robert is a cautionary tale about the importance of responsible leadership and the dangers of allowing power to fall into the wrong hands.