Biblical Context:
The desperate act by the King of Moab is a significant event recorded in the Old Testament, specifically in 2 Kings 3. This chapter details the conflict between the coalition of Israel, Judah, and Edom against Moab. The Moabites, led by King Mesha, had previously been subjugated by Israel and were required to pay a substantial tribute. However, after the death of King Ahab of Israel, Mesha rebelled against Israelite control.

Narrative Account:
The narrative unfolds as Jehoram, the son of Ahab, ascends to the throne of Israel and seeks to reassert control over Moab. He allies with Jehoshaphat, the King of Judah, and the King of Edom to march against Moab. The coalition forces find themselves in a dire situation due to a lack of water, but through the intervention of the prophet Elisha, God miraculously provides water for the troops and their animals.

The coalition then engages the Moabites in battle, achieving significant victories and causing devastation to the land of Moab. As the battle intensifies, the Moabite forces are pushed back to their capital city, Kir Hareseth.

The Desperate Act:
In a moment of desperation, King Mesha of Moab performs a shocking act. The biblical account in 2 Kings 3:26-27 states: "When the king of Moab saw that the battle was too fierce for him, he took with him seven hundred swordsmen to break through to the king of Edom, but they could not prevail. So he took his firstborn son, who was to succeed him as king, and offered him as a burnt offering on the wall. And there was great wrath against Israel, so they withdrew and returned to their own land."

This act of human sacrifice, particularly of his heir, was a desperate attempt by Mesha to invoke the favor of his gods and turn the tide of battle. The text notes that this act resulted in "great wrath against Israel," leading to the withdrawal of the coalition forces. The exact nature of this "wrath" is debated among scholars, with interpretations ranging from divine displeasure to a psychological impact on the Israelite forces.

Theological and Historical Implications:
From a theological perspective, the act underscores the stark contrast between the worship practices of the Israelites and those of the surrounding nations. The Israelites were expressly forbidden from engaging in human sacrifice, as outlined in the Mosaic Law (Deuteronomy 12:31). The Moabite king's actions highlight the depravity and desperation that can arise from pagan practices.

Historically, this event is significant as it marks a turning point in the conflict between Israel and Moab. The withdrawal of the Israelite coalition allowed Moab to regain a measure of independence, as evidenced by the Mesha Stele, an ancient Moabite inscription that corroborates the biblical account of Mesha's rebellion and subsequent victories.

Cultural Context:
The act of human sacrifice, while abhorrent to the Israelites, was not uncommon in the ancient Near East. It was often seen as a means to appease deities in times of extreme crisis. The Moabites, like many other ancient cultures, believed that such sacrifices could influence the outcome of battles and secure divine favor.

Conclusion:
The desperate act by the King of Moab serves as a sobering reminder of the lengths to which individuals and nations might go when faced with existential threats. It also provides insight into the religious and cultural dynamics of the ancient Near East, as well as the distinctiveness of Israelite worship and ethics.