Saul is dead. His son Jonathon is dead. Although he was initially kept from battle, David turned a defeat into a victory.
Eventually, the tribes of Israel conclude that David should be their king.
Or, am I supposed to be reading this as finally the people of Israel catch on to what the Lord has long planned?
The lectionary has skipped over a lot of intrigue. Are differences between factions no longer important after the leadership is decided? (If we read ahead, we see that the tribes will split apart after Solomon's reign).
Back to the king part. When the people had first wanted a king, the Lord had forecast for them what life with a human king would be like (see 1 Samuel 8), but they wanted one anyway. They just weren't able to trust the rule of the Lord unmediated by a human king.
Psalm 48 is an assertion of the greatness of the Lord. Even kings submit themselves to God. If only.