Compare the marginal reference. Mesha, when his sally failed, took, as a last resource, his first born son, and offered him as a burnt-offering to appease the manifest anger of his god Chemosh, and obtain his aid against his enemies. This act was thoroughly in accordance with Moabitish notions.
And there was great indignation against Israel - Either the Israelites were indignant with themselves, or the men of Judah and the Edomites were indignant at the Israelites for having caused the pollution of this sacrifice, and the siege was relinquished.