The Iliad was about the last couple of weeks of the Trojan War, specifically the really significant events that happened those last couple of weeks, and the Greek siege of the city of Troy.
The answer is the interest groups. It is because this is a
group where in people are joined together because of the shared purpose that
they all have and a way that they work together because of the fact of
promoting their interest, influencing others and protecting their own. They
will find outside strategies to be useful because their group are likely to
take part in social and political systems.