In this chapter, Adonijah attempts to inherit the kingdom from David, but David gives it to Solomon instead.
This chapter begins with an ending, as David's life comes to an end. It's interesting to note that Samuel does not end precisely at the death of David; in fact, the primary story arc of Samuel ends when David has secured his kingdom (2 Samuel 20), but probably years before his death. We can contrast this to Genesis 50 and Deuteronomy 34, which both end their respective books with the death of an honored figure. 2 Samuel ends with a song and a "final word" that seems to anticipate David's death, just as Jacob's final words (Gen 49) anticipated his death, but strangely, David's death is missing. In that sense, 2 Samuel is breaking with convention.
All of this is relevant to 1 Kings 1 because David is still alive in this chapter, and David's life forms a thematic connection between the end of 2 Samuel and the beginning of this book. Even though Kings and Samuel were written as separate books, there is a clear continuity between them, and for many purposes they can be treated as a single, extended topic, "the history of Israel from Samuel to the exile to Babylon".
However, David is going to die in the next chapter, which means that his involvement in this book is limited to just setting the stage for his own succession. It's possible the author of Kings included a reference to David because he is trying to establish the legitimacy of the royal dynasty through Solomon.
Indeed, this chapter begins with David "old, advanced in years". At this point, David is in practice a "lame duck" king. He is not an effective ruler, but he still holds considerable political influence because most of the court officials are deeply loyal to him personally.
Adonijah is David's fourth-born son, directly after Absalom in age priority. Absalom directly revolted against David and temporarily drove David into exile across the Jordan. Absalom took advantage of disaffection with David's reign, amongst the men of Hebron and Judah who felt they were losing influence, and amongst Benjamin and the northern tribes that were perhaps still bitter about the destruction of the house of Saul. Nevertheless, David's men defeated Absalom, Absalom died and in the ensuing years, David appears to have secured his position as king over Israel.
With Absalom dead, Adonijah is ostensibly next in line for inheriting the throne. However, as we discover in this chapter, David appears to have declared Solomon to be his successor. There are several possible reasons why this might have happened. One is that Nathan prophesied or implied that Solomon would reign as king when he said that "the LORD loved [Solomon]" (2 Samuel 12:24-25). Another is that David still felt guilty about killing Uriah and his adultery with Bathsheba, so it's possible he declared Solomon his successor as some sort of compensation for the harm he did to Bathsheba. And then there are more practical reasons, like if Solomon won David's approval through his words or actions. However, priority of inheritance usually goes to the oldest living son, so at least to me, it's a bit surprising that David would give the kingdom to Solomon, because it appears to break with the cultural traditions of the day.
Adonijah also objects to the kingdom going to his younger half-brother. In many ways, Adonijah's revolt is similar to Absalom's. They are both described as handsome, striking young men. Both of them get chariots and a group of 50 runners to go before them, in essence claiming the trappings of power. Both of them aspired to be king. The biggest difference is that Adonijah is not actually seeking to overthrow David; he is seeking to overthrow Solomon. In essence, what Adonijah is trying to do is gather enough of David's officials into his camp that he can claim the throne and disinherit Solomon. The reason why Nathan says he is trying to save Bathsheba and Solomon's lives (v. 12) is because if David dies and Adonijah becomes king, then Adonijah would most likely finish the job by killing Solomon and anyone else who opposes him.
The biggest thing holding Adonijah back at this point is that, while David still lives, David holds the loyalty not just of his court officials, but also of the populace at large, and in the end this is Adonijah's undoing.
Next, I would like to talk about the men who joined Adonijah, especially Joab and Abiathar. I have written many times about Joab's strained relationship with David. David already tried to demote Joab once, and Joab responded by killing his own replacement and taking back his position over the army. We also know that Joab has been historically loyal to David. However, Joab knows that if Solomon takes power, then it is very likely that Joab would once again be thrown out of office and possibly even killed. Basically, the political aspect works like this. If you side with the guy in power, then maybe he will like you and maybe not, but since he is already in power, he will not owe you anything. If you side with a guy who is not in power, and help get him into power, then he owes you, and it strengthens your own position too.
It was like when Abner put Ish-Bosheth on the throne. While Ish-Bosheth was the king, Abner was the kingmaker and in the end, Abner proved to be the more influential person. Joab would know, because Joab killed Abner. I am betting that Joab wants to do something similar, putting Adonijah on the throne and thereby maintaining his own power.
Abiathar is an interesting case. We know much less about Abiathar than we do Joab. What we do know is that he was the sole survivor of Nob and he joined David back when David was himself hiding from Saul. Abiathar served David for years. At a certain point, Abiathar and Zadok became "the priests" (for one example, see 2 Samuel 20:25). This is interesting because according to convention, there is a single high priest and everyone else in the priestly structure are subservient to this sole authority figure. The priesthood, like many other parts of Israel's society, is patriarchal, which typically means that the office of the high priest passes down from father to oldest living son, descending from Aaron. The priesthood doesn't really have a concept of "co-high priests". Therefore, I would be willing to bet that with two senior figures, some sorting out is inevitable.
Because Abiathar sides with Adonijah, I would be willing to bet that David (or Solomon) had promised to make Zadok the new high priest, although such events are not recorded.
Therefore we see a relatively consistent story between Adonijah, Joab and Abiathar. It is an alliance of a would-be king, a soon-to-be-deposed general, and an almost-high priest. All three of them are aspiring to power and the top job, and all three of them would be relegated to insignificance if Solomon takes power. They are all lingering on in power (if they did not have power, they would not be threatening to take the kingdom), but they are all in decline.
The part that interests me is in verse 9, when it says that "the king's sons" all supported Adonijah, except for Solomon. I'm interested because I don't see what they have to gain from Adonijah gaining power. So, I don't quite understand that.
Anyway, that's enough for the setup. For the actual events, Adonijah begins his coup with a party. The way I interpret it is that Adonijah is trying to act as if he is already king, so that everyone starts to believe it, and if he does this well enough, he will convince all of the people that he is king and (in effect) become king. It's funny how a celebration can be such a threatening event though. Nathan and Bathsheba know that their only chance of stopping Adonijah is while David is still alive, because David alone commands the loyalty of the people and his men.
King David's response to Adonijah is very much in the same vein. Rather than the bloodshed that characterized Absalom's rebellion, in this case the war is very much about perception, trying to create the public perception in the nation that one man or the other is king. Hence, David's response is entirely about intentional, public symbolism. Solomon is seated on the king's mule, publicly anointed king, proclaimed king, and then taken back to sit upon David's throne (literally).
Adonijah's revolt started with a party, and it is cut short by an even larger, competing party, when the celebration over Solomon's coronation causes the earth to "shake with noise" (v. 40). When Jonathan the son of Abiathar comes and brings them bad news, it is not a defeat in battle, it is the celebration that another man has been proclaimed king. David himself is publicly celebrating and worshiping God while declaring to anyone who will listen that Solomon will succeed him.
I love the contrast between the massive celebration in Jerusalem and the distress filling all the guests of Adonijah. In fact, the conflict ends without a single man dying. The men with Adonijah are afraid because they know that by siding with Adonijah, they are in opposition to Solomon, and it is a perilous thing to oppose the king. They also understood that when the larger city celebrated Solomon, they sided with Solomon and just by the weight of sheer numbers, Adonijah was already sunk.
Adonijah himself knew it, so rather than try to run away or gather more men, he goes straight to the altar, a plea for mercy. Now, there are two altars in the tabernacle that have horns. There is the bronze altar of burnt offerings (Ex 27:1-2) and the golden altar of incense (Ex 30:1-3). So which altar does verse 50 refer to? The answer is more likely than not, the bronze altar of burnt offerings. The reason is that the bronze altar was placed openly in the court of the tabernacle, and while the court is not exactly open to the public, it is close. The golden altar of incense, however, is placed within the tabernacle itself, in the holy place, and only priests are allowed to enter there.
At this point, Adonijah has no chance of fighting Solomon and simply resigns himself to his fate. Solomon spares him. However, Solomon is now aware that all of Adonijah, Joab and Abiathar have tried to directly subvert his reign, and he is unlikely to forget it. That is, if they were at risk of being demoted before, they are at risk of being executed now.