1 Chronicles Chapter 11

The first 8 verses are parallel to 2 Sam 5.

2022 - This seems like an abbreviated version of David's coronation and first actions, yet there are things  here I don't remember from 2 Sam 5.  Particularly that David says whoever attacks the Jebusites first will be commander of the army, and that is how Joab becomes commander.  This is when Jerusalem was taken.  Remember that God had not yet chosen a place to put his name forever at this point.  The tabernacle was still in service, and even that was not in Jerusalem.  We don't know why David chose Jerusalem...except in hindsight.  It was a walled and fortified city, and David chose to go and take it and live there rather than continue to live in Hebron.  What were the differences?

Then Chronicles lists the chiefs, the mighty men, who served David.

There were "Three".  The first of "The Three", Jashobeam, killed 300 men single-handedly.

Second of the three was Eleazar.  He made a stand against the Philistines and turned the battle around.

I don't see the third named.

2022 - I am wondering if the third mighty man would have had to be Joab himself? 

Other mighty men, and their exploits, are then chronicled.

All thirty of the thirty chiefs are named, as are their "cities of origin".  Many came to serve David.