Those Amalekites are like a hydra, you cut them off and they just grow back. Remember when Saul killed all of them but the king, and then Samuel got angry and killed the king? Well, here they are again, just a few years later, and there are somehow enough of them to sack David's city of Ziklag. They take the women and children hostage, including David's two wives. David weeps but hey buddy, at least your wives are alive. You have more of a tendency to slaughter people mercilessly in these situations.
The people want to stone David for this kidnapping, which doesn't seem like it would accomplish much. He asks for the magic yes/no coin and asks if he should pursue his enemies and take his wives back. What coin is going to say no to that? So he takes his men and heads after the Amalekites.
As he's passing through a field, his men find a little Egyptian boy. They give him bread and water and when he's recovered, they ask his story. He was the Amalekites' slave, abandoned in the retreat because he was sick. David asks if he can help them find the Amalekites. He agrees, on the condition he be set free.
David finds them partying it up after their conquest and slaughters all but 400 who were still sober enough to saddle their camels and ride away. David, meanwhile, claims his
He returns in triumph, and gives everybody's families back, but keeps the treasure and animals back for the people who helped him. This then becomes a statute.
More god-sanctioned killing. This time, the Philistines attack the Israelites and kill Saul's three sons, just as predicted. Saul gets speared by an arrow and begs his armour bearer to kill him. The man refuses, so Saul took a sword, and fell upon it. (v. 4)The armour bearer does likewise. Is that the origin of that expression?
The Israelites see this and decide against defending the cities, so the Philistines just sort of... walk into victory. They stumble upon the bodies and cut off Saul's head and send it around their territory like a trophy. So Saul's men were so loyal they didn't even bother to take his body with them when they retreated? His body and armour are similarly displayed. Only after word gets back to Israel that their former king's accoutrements have become a travelling circus do the men of Jabeshgilead sneak into the Philistine's territory and steal them back. Then they bury them and have a feast.