Judges 20:33-36

33And all the men of Israel rose up out of their place and set themselves in array at Baal-tamar, and the men of Israel who were in ambush rushed out of their place from Maareh-geba.
Some Septuagint manuscripts place west of Geba
34And there came against Gibeah 10,000 chosen men out of all Israel, and the battle was hard, bbut the Benjaminites did not know that disaster was close upon them. 35And the Lord defeated Benjamin before Israel, and the people of Israel destroyed 25,100 men of Benjamin that day. All these were men who cdrew the sword. 36So the people of Benjamin saw that they were defeated.

The men of Israel gave ground to Benjamin, because they trusted the men in ambush whom they had set against Gibeah.
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