The war between the house of Saul and the house of David lasted a long time. David grew stronger and stronger, while the house of Saul grew weaker and weaker.
References for 2 Samuel 3:1
Sons were born to David in Hebron: His firstborn was Amnon the son of Ahinoam of Jezreel;
References for 2 Samuel 3:2
his second, Kileab the son of Abigail the widow of Nabal of Carmel; the third, Absalom the son of Maakah daughter of Talmai king of Geshur;
References for 2 Samuel 3:3
the fourth, Adonijah the son of Haggith; the fifth, Shephatiah the son of Abital;
References for 2 Samuel 3:4
and the sixth, Ithream the son of David’s wife Eglah. These were born to David in Hebron.
During the war between the house of Saul and the house of David, Abner had been strengthening his own position in the house of Saul.
References for 2 Samuel 3:6