Why is Agamemnon so stubborn in Iliad Book 1

From the outset of the narrative, Agamemnon is shown to be
a ruler who demands respect.  He is one that examines everything through the lens of
respect.  War is fought as an exercise to reflect this respect and what is gained
through war and through politics must be filtered through the prism of respect.  This
ego is the reason why he comes across as so stubborn in the first book.  He does not
easily capitulate from originally stated demands.  At the same time, his role as a royal
compels him to believe that he is worthy of everyone's acquiescence, refusing to give
his at most times.  Agammenon's rivalry with Achilles is also predicated upon the idea
that a soldier has no right to determine what a king should do.  It is this presence of
will, the faith in the individual subjective, and the belief that respect has to drive
all and determine the value of all else that ends up making him so stubborn in the first
book and throughout the narrative.