Chapter 1

An Amalekite comes to David's camp, and tells David that Saul and Jonathan are dead.  David asks how he knows.  The Amalekite claims to have killed Saul himself, at Saul's request, and he's brought Saul's crown and armlet to David.  (But in 1 Samuel, it says that Saul fell on his own sword, so the Amalekite is not being 100% truthful.)

2025 - What was an Amalekite doing in Saul's camp anyway?  It was the Amalekites from whom David had just recovered his wives and the wives and children of all his men.  These were no friends of Israel - they would plague Israel for many years yet to come.  Why would he come to David and make such a claim?

David and his men tear their clothes and mourn.  Then David confronts the messenger, and asks him where he gets off killing God's anointed?  By his own words, the Amalekite has condemned himself.  David has the messenger killed.  Wonder if this is where "killing the messenger" came from?

The rest of the chapter is a lament for Saul and Jonathan.  The phrase "how the mighty have fallen" is repeated a couple of times in the ESV.  Older translations render it "how have the mighty fallen".