Saul was chosen the first king of Israel after the sons, and potential successors, of the high priest Samuel were rejected by the people as corrupt. God permitted the establishment of the monarchy, but made his displeasure evident. Later, he told Samuel how he would meet the man who was to be anointed the first king of Israel.
The following day, Samuel met Saul, the son of Kish of the tribe of Benjamin. In what was undoubtedly a providential set of circumstances, Saul had been searching for some donkeys that his father had lost. After hunting for them for three days, he was about to turn back when the servant accompanying him suggested he meet the seer who lived in the neighborhood. The seer, was of course, Samuel, who was expecting him.
Samuel invited him for a meal and afterwards, as Saul was leaving, he anointed Saul as king over Israel, giving him three signs in confirmation of his call to be king.
As Saul turned to leave Samuel, God changed Saul's heart, and all these signs were fulfilled that day. When they arrived at Gibeah, a procession of prophets met him; the Spirit of God came upon him in power, and he joined in their prophesying. When all those who had formerly known him saw him prophesying with the prophets, they asked each other, "What is this that has happened to the son of Kish? Is Saul also among the prophets?"
(1 Samuel 10:9-11)
Soon after, it was time to make the anointing public and Samuel accordingly summoned the people to a solemn assembly at Mizpeh. The gathering drew lots and Saul was chosen.
Samuel said to all the people, "Do you see the man the LORD has chosen? There is no one like him among all the people." Then the people shouted, "Long live the king!"
(1 Samuel 10:24)
The new king returned home with an entourage of sorts, and resumed the quiet toils of his former life. But soon he was drawn into his new role, when Nahash the Ammonite went up and besieged Jabesh Gilead. Saul rallied the tribes of Israel and in battle gained a complete victory over the invaders. Amid the universal joy occasioned by this victory he was now fully recognized as the king of Israel.
Flushed with success, Saul undertook the difficult task of freeing the land from its hereditary enemies the Philistines, but soon made a series of very serious blunders, beginning with the offering of a sacrifice, which was to be performed only by the priests. It was this foolish and presumptuous disobedience to God that cost him the kingship, which would later be taken over by David.
Saul's behavior then degenerated from unwise to insane. At one point, he ordered his military forces to go without food until they had defeated the enemy, and then attempted to have his own victorious son Jonathan executed for disregarding the foolish order.
His insanity was heightened by the feelings of jealousy he harbored toward David, his successor, who proved to be a valiant lad when he slayed the famous Goliath. His jealousy increased with David's military success and popularity with the people, ultimately resulting at an attempt to murder David, which made the young man flee.
In yet another failure in judgment and obedience to God, Saul consulted the witch of Endor in which his doom was predicted by an apparent appearance by the dead Samuel.
Saul died during a battle with the Philistines the very next day, along with all this three sons. Wounded critically, he impaled himself on his sword, rather than be killed by the enemy.