The stratagem described is exactly that by which Joshua took Ai (marginal reference).

Israel set liers in wait - Though God had promised them success, they knew they could expect it only in the use of the proper means. They used all prudent precaution, and employed all their military skill.

And Israel set liers in wait round about Gibeah. For though they were assured of success and victory, yet they thought proper to make use of means: and though their numbers were very great, they had recourse to art and stratagem, and set an ambush in divers places, much in like manner as Israel did for the men of Ai; the two cases being pretty much similar; this ambush was set in the night, as Josephus says (s),

(s) Ut supra, (Antiqu. l. 5. c. 2.) sect. 11.

The Victory on the Third Day's Engagement. - Judges 20:29. The account of this commences with the most important point, so far as their success was concerned: Israel set liers in wait (troops in ambush) round about Gibeah.

And Israel set liers in wait round about Gibeah.

20:29 Liers in wait - Though they were assured of the success, by a particular promise, yet they do not neglect the use of means; as well knowing that the certainty of God's promises doth not excuse, but rather require man's diligent use of all fit means for the accomplishment of them.

Jud 20:29-48. They Destroy All the Benjamites, Except Six Hundred.

29-48. And Israel set liers-in-wait round about Gibeah-A plan was formed of taking that city by stratagem, similar to that employed in the capture of Ai [Jos 8:9].

17:7-13 Micah thought it was a sign of God's favour to him and his images, that a Levite should come to his door. Thus those who please themselves with their own delusions, if Providence unexpectedly bring any thing to their hands that further them in their evil way, are apt from thence to think that God is pleased with them.