The struggle between weakness and strength is a constant theme in Lord of the Flies, taking place externally in tribal conflict and, more importantly, internally in the minds of the characters.
The internal conflict is more profound, and its results are more surprising, because it is clear that strength will always defeat weakness in battle. In an internal, psychological struggle, however, weakness can prevail, and it often does. This is arguably what happens to Simon when he begins to see the Lord of the Flies not as a pig's head on a stick but as an oracle. Strength is dependent on sanity, which means that not only Simon, but characters such as Jack and Roger, give way to weakness.
The internal struggles complicate what is happening on the surface. Jack seeks overall control of the island and uses his strength and that of the hunters to obtain it by terrorizing the other boys. However, Jack is not in control of himself, while Piggy, externally a weaker character, at least remains master of his own mind. The weakness to which all the boys succumb in the absence of a structured civilization is shown at the end of the book by their lack of restraint in front of the naval officer. The officer represents authority and strength and is disappointed to see that the boys have given way to weakness, even if he does not understand the nature of the weakness that has overwhelmed them.