The books of 1st and 2nd Samuel, in the original Hebrew Bible, were a single book. Actually, context seems to imply that that 1Samuel right through 2Kings was more or less a solid piece of historical narrative. What we're looking at here is the history of the Jewish monarchy, with 1Samuel being events leading up to the coronation of David, and 2Samuel being the story of David as King. I've often wondered why it's not called the book of David, since he figures prominently throughout both books of Samuel, while Samuel is not even named in 2Samuel.
As usual, the SAB has some things to say in the overview of the book that I agree with heartily, although of course it will come out that I disagree with the interpretation when I address specifics. Hemorrhoids and foreskins? It's a wacky book alright, and even the person who believes in God but doesn't know the Bible really well is going to find more than a few surprises in here, many not pleasant.
Why is it that it seems God appoints kings not to keep the peace so much as wage war? As noted, Saul eventually is deposed as king essentially for his refusal to commit genocide. And against the Amalekites, which is an issue I've already had to address, but will probably need to delve into in more detail. On the other hand, God is quite pleased with David, who, as the SAB puts it rather well, "is always happy to kill for God." Really, a lot of this meshes in with the issues of the purpose of the conquest of Canaan, which was left unfinished in Joshua's day, but pretty much completed by David. It also has to do with larger issues of the nature of God and the Judeo-Christian worldview which I have opined on in general in a previous post. What God's looking for in a king is not what we look for in a king, as the Bible itself says. And I don't think we should be looking for the same thing in a king that God looks for, because we're not Israel, and not a monarchy, but that's my two cents.
This is a strange book in various ways for the fact that it introduces politics into the Bible as never before, and also in that it's one of the first books to really be clearly and openly a book edited from multiple sources. It makes for a different feel, that's for sure, but at least we're largely back to a straightforward linear story, at least for a while.