John Gill Commentary 1 Chronicles 12:38

"All these being men of war, that could order the battle array, came with a perfect heart to Hebron, to make David king over all Israel: and all the rest also of Israel were of one heart to make David king." — 1 Chronicles 12:38 (ASV)

All these men of war that could keep rank
Well disciplined men:

came with a perfect heart to Hebron to make David king over Israel ;
they were all of one mind, and quite hearty and sincere in fixing David on the throne of all Israel:

and all the rest also of Israel were of one heart also to make David
king ;
those who came not were of the same mind; it was the unanimous voice of the people that he should be their king.