“And the war.” 2 Samuel 3:1 should have been the concluding summary verse of chapter 2. The war, started in chapter 2, went on for a long time.

“between the house of Saul and the house of David.” The war is not categorized as a full-fledged civil war between warring Israelite tribes, but rather is a power struggle for control of Israel between the house of Saul (his descendants and followers) and the house of David. Other Israelites would have certainly been pulled into the conflict, but it was a battle for the kingship of Israel between David and Saul’s house.