A real challenge comes for Saul's leadership when Samuel doesn't show up at the appointed time and he is left to decide what to do.  Samuel told Saul that he would arrive after seven days to offer a sacrifice to the Lord before going into battle.  Saul took matters into his own hands and gave up his right to the throne.  His mistake seems harmless: to offer God a sacrifice before going into battle.  So why was it such a big deal?  The problem is that Saul was caught up in himself.  If the battle was lost, then he would look bad – he would look like a failure of a king.  He feared that their time was running out, so he (like so many others in Old Testament history) tried to manipulate God into winning the battle for him.  Saul didn't want to win the battle for the Lord; Saul wanted to win the battle for himself!  It was at that point that the Lord decided that he was no longer fit to lead.  God cares about the heart of the leader, and when a spiritual leader beings to make things about himself, God takes his authority away.