Samuel warned the Israelites that if they continued to sin, God would destroy both the people and their king.
A king, or any other institution, cannot shield the people from punishment for their sins against God. No one can "institutionalize" justice, peace, and happiness except our Lord Jesus!
King Saul started off well. He was humble, prudent, obedient to God, and brave for his people against the enemy.
But Saul quickly began to wobble, when he disobeyed the commandment regarding the sacrifice. He was afraid the people would desert him in the face of a vast host of the Philistines, and he decided to make an offering in order to keep the people from leaving.
Soon after that, Saul descended into rash behavior, ill-considered actions that provoked the people to sin, and then, in a paranoid manner, seeking to enforce his foolish dictates in order to vindicate himself. The people finally had to put a stop to Saul before he put his own valiant son Jonathan to death for no good reason.
Saul at first sought to consult with the Lord, but the Philistines were in retreat following Jonathan's exploits against the garrison.
Saul spoiled that great victory by making a foolish order that no one eat anything all day during the rush and heat and exertion of the running battle.
This resulted in the people growing weak and faint, and when evening was come, they rushed to kill and eat of the prey they had seized, without draining the blood, which was a gross, notorious sin against God's commandment.
But Saul was more preoccupied with the fact that Jonathan had eaten a little honey, not knowing the king's commandment. Saul swore to put Jonathan to death for it!