His sister Tamar having been violated by David's eldest son Amnon, Absalom, after waiting two years, caused his servants to murder Amnon at a feast to which he had invited all the king's sons (2 Samuel 13). After this deed he fled to Talmai, "king" of Geshur (see Joshua 12:5 or 13:2), his maternal grandfather, and it was not until five years later that he was fully reinstated in his father's favour (see Joab.)
Four years after this he raised a revolt at Hebron, the former capital. Absalom was now the eldest surviving son of David, and the present position of the narratives (15-20)--after the birth of Solomon and before the struggle between Solomon and Adonijah---may represent the view that the suspicion that he was not the destined heir of his father's throne excited the impulsive youth to rebellion.
All Israel and Judah flocked to his side, and David, attended only by the Cherethites and Pelethites and some recent recruits from Gath, found it expedient to flee. The priests remained behind in Jerusalem, and their sons Jonathan and Ahimaaz served as his spies. Absalom reached the capital and took counsel with the renowned Ahithophel. The pursuit was continued and David took refuge beyond the Jordan.
A battle was fought in the "wood of Ephraim" (the name suggests a locality west of the Jordan) and Absalom's army was completely routed. He himself was caught in the boughs of an oak-tree, and as David had strictly charged his men to deal gently with the young man, Joab was informed. What a common soldier refused to do even for a thousand shekels of silver, the king's general at once undertook. Joab thrust three spears through the heart of Absalom as he struggled in the branches, and as though this were not enough, his ten armour-bearers came around and slew him.
The king's overwhelming grief is well known. A great heap of stones was erected where he fell, whilst another monument near Jerusalem (not the modern "Absalom's Tomb," which is of later origin) he himself had erected in his lifetime to perpetuate his name (2 Samuel 18:17 and following). But the latter notice does not seem to agree with 14:27 (compare 1 Kings 15:2).
Initial text from 1911 encyclopedia