Take a look at P. Derchain, "Le plus anciens temoignages de sacrifices
d'enfants chez les Semites occidentaux" in VT 20 (1970) 351-55.
According to Hobbs (Word Biblical Commentary) the wrath implies a) the
battle suddenly went against them or b) they withdrew from the field in
disgust.
Cohn (Berith Olam) opines that the verse is from the perspective of Moab and
explains Israel's withdrawal.
Jim
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Jim West
Quartz Hill School of Theology
Adjunct Professor of Biblical Studies