At the time of chapter thirty-one, the Philistines were fighting against Israel (v. 1a).
The men of Israel fled from the Philistines and fell down slain before them on Mount Gilboa (v. 1b).
The Philistines chased Saul and his sons and struck down his three sons, including Jonathan (v. 2).
The battle bore heavily against Saul, and he was badly wounded by the archers. Saul asked his armor bearer to draw his sword and thrust him through with it, but the armor bearer refused. Then Saul took his sword and fell on it (vv. 3-4).
Saul's armor bearer fell likewise on his sword and died with him (v. 5). Therefore, Saul, his three sons, and his armor bearer died that day together (v. 6). This corporate death was God's fair judgment on the one who had rebelled against Him, had usurped Him, and had become His enemy. Saul had set up his own monarchy, abusing to the uttermost all the divine things given to him.
The men of Israel on the other side of the valley and on the other side of the Jordan forsook the cities and fled, and the Philistines came and dwelt in them (v. 7).
The next day the Philistines came to strip the slain and they found Saul and his three sons fallen on Mount Gilboa. They cut off Saul's head and stripped off his armor and sent them all around throughout the land of the Philistines, in order to announce the good news in the houses of their idols and to their people. Then they put Saul's armor in the house of Ashtaroth and fastened his body to the wall of Beth-shan (vv. 8-10). What a terrible ending!
The inhabitants of Jabesh-gilead heard what the Philistines had done to Saul, and all the valiant men went all night and took the body of Saul and the bodies of his sons from the wall of Beth-shan and burned them and buried them at Jabesh. Then they fasted seven days (vv. 11-13).