I Samuel - Chapter 14
A LOT of Stuff Happens
On his own initiative, Shaul's son Jonathan took his armor-bearer and went to spy out the Philistine camp. Nobody knew that they had gone. Jonathan knew that, when they saw Philistines, if the enemy said "Halt - we'll come to you" that they were strong and confident, but if they said, "Hey, come here," then they were afraid of an ambush and that G-d would allow the Jews to defeat them.
They approached the Philistine camp and the guards saw them. They said, "Hey, come here! We want to tell you something!" Jonathan knew from the sign that G-d would deliver the Philistine army into the Jews' hands, no matter how unevenly matched they appeared to be. Jonathan and his armor-bearer then ran through the camp, routing the Philistine army, whom G-d had struck with fear.
Shaul's army saw the Philistine camp panicking and running amok. Clearly, something was up. They looked to see who was missing and realized that it was Jonathan and his attendant. Meanwhile, the crazed Philistines were wiping each other out in their panic and the Jews who had gone into hiding returned to fight.
In order to keep the people focused on the task at hand, Shaul decreed a fast. On pain of death, no man was to eat until nightfall. The battle raged into the forest where honey was dripping, but nobody tasted it because of Shaul's oath. Jonathan, however, hadn't been with the rest of the army at the time, so he didn't know about the oath. He ate some honey, which reinvigorated him. One of the other soldiers told him about his father's oath, with which Jonathan disagreed. (Shaul's reason was so that the people would not be distracted; Jonathan felt the army could use the extra energy.)
The Jews defeated the Philistines - clearly with G-d's help! They settled down to eat, but they ate "on the blood." The exact meaning of "on the blood" is unclear. It does NOT appear that they ate the blood itself (which is a very serious sin). More likely, they ate the meat of the sacrifices before the blood was sprinkled on the altar. (There are other explanations offered by the commentators.) Shaul saw this and put a stop to it. He set up an altar for the sprinkling of blood to obviate the problem.
Shaul then had the Kohein Gadol (High Priest) consult G-d via the Urim and Tumim as to whether or not they should pursue the remaining Philistines. G-d did not reply, which had never happened before. Shaul knew from this that there was still a sin hanging over the heads of the nation and he was determined to find out what it was. He said, "No matter who it is, even my own son Jonathan, shall die."
Shaul was able to determine that it was, in fact, Jonathan! He asked his son what he had done and Jonathan told him that he violated his father's oath of a fast. Shaul was prepared to carry out his word - it wouldn't do for the king to be guilty of favoritism! But the people rallied to Jonathan's defense, as the victory had been brought about through his actions. Because the people stood up for him, Jonathan was spared.
Shaul broke off pursuit of the Philistines, who retreated to their territory. Shaul strengthened his army and consolidated his rule. He fought against the nation's enemies on all sides.