Judges 3:2

He left those nations simply because he wanted to teach the subsequent generations of Israelites, who had not experienced the earlier battles, how to conduct holy war. ¹ 

(he did this only to teach warfare to the descendants of the Israelites who had not had previous battle experience):

only in order that the generations of the sons of Israel might be taught war, those who had not experienced it formerly).

He did this to teach warfare to generations of Israelites who had no experience in battle.

He did it to train the descendants of Israel, the ones who had no battle experience, in the art of war.

Only because of the generations of the children of Israel, for the purpose of teaching them war—only those who up till then had no experience of it;

(it was only that successive generations of Israelites might know war, to teach those who had no experience of it before):

( this was only so that the generations of the children of Israel might be taught to know war, at least those who had not formerly known it),

He left those nations simply because he wanted to teach the subsequent generations of Israelites, who had not experienced the earlier battles, how to conduct holy war. ¹ 

¹ tn The Hebrew syntax of v. 2 is difficult. The Hebrew text reads literally, “only in order that the generations of the Israelites might know, to teach them war – only those who formerly did not know them.”

sn The stated purpose for leaving the nations (to teach the subsequent generations…how to conduct holy war) seems to contradict 2:22 and 3:4, which indicate the nations were left to test Israel’s loyalty to the Lord. However, the two stated purposes can be harmonized. The willingness of later generations to learn and engage in holy war would measure their allegiance to the Lord (see B. G. Webb, Judges [JSOTSup], 114-15).