If you recall, Israel had been under Philistine domination for quite some time. The Philistines had declared that no Hebrew was to be allowed swords or any other weapons, and they had outlawed Hebrews from being blacksmiths to prevent any weapons from being made illegally. However, Saul was planning an insurrection, so he convinced all the Hebrews to carry their farming implements–plowshares, mattocks, axes, etc–to their local Philistine blacksmiths for sharpening. Saul, and his son Jonathan, had swords, however.
This is maybe 2-3 years after the anointing, maybe 12-13, since Saul, who appeared to be a young man at the anointing, now has a son old enough to fight in battle, so anyway, at some point in the future, near or far, it doesn’t matter, because this is the time of the gods, Saul gathered up an army of 3000 Hebrews to fight the Philistines. He had charge of 2000 in Michmash while his son Jonathan had charge of the other 1000 in Gibeah.
Jonathan’s army defeated the Philistines at Geba, so the Philistines sent an army of 30,000 chariots and 6000 cavalry, plus foot soldiers, to Michmash to punish the Hebrew insubordination. Most of the Hebrews then hid out in caves and cisterns and tombs or fled across the Jordan to Gad and Gilead.
Meanwhile, Saul had declared victory and called for the people to join him at Gilgal to sacrifice. Saul waited and waited for Samuel to come join him at Gilgal as he had promised to always do, within seven days. But Samuel didn’t come and the people were getting restless. So on the seventh day, Saul was all, well I guess we should go ahead with the sacrifice.
Just as the burnt offering was incinerated, Samuel hurried up, exclaiming, What have you done?! Why didn’t you wait for me? Saul was all, well I did, but it didn’t look like you were coming, and the people were getting restless, and we really need to get on the road to Michmash since the Philistines are running riot there, so we performed the ceremony without you.
Samuel was shaking his head in dismay and then was all, Too bad for you for being so impatient because now you’ve angered God. You know how particular It is about Its meat. If Its meat isn’t prepared exactly as It directs, Its wrath rains down. God had planned on making your family the once and future king of Israel, but now, you’ve gone and blown it. You’ll remain king, but your sons will not follow. God is telling me that It has found someone It likes better.
Samuel walked away, and Saul marched the forces back to Gibeah. Then Saul, Jonathan and a troop of 600 men camped at Geba to take on the Philistines, who had been sending raiding parties out toward Ophrah, Shuel, and the Vallley of Zeboin.