Nevertheless the king's word prevailed against Joab. Therefore Joab departed, and went throughout all Israel, and came to Jerusalem.
"The major reason for taking a census in Israel was to lay the basis for levying taxes (Exodus 30:12; Numbers 3:40-51) or registering men for military service (Numbers 26:1-4)." [Note: Thompson, p. 160. Cf. 21:4-7.] 