2 Kings / Question
When the sun shone on the water, the Moabites saw it from a distance as red like blood. They concluded the kings had fought each other and that there was plunder to take. So they went to Israel’s camp, where Israel rose and struck them (2 Kings 3:22–24).
In 2 Kings 3:21–25, Moab mobilizes to meet the invading kings at the border. At sunrise they misread the sight of water as blood, conclude the allied armies have killed each other, and rush forward to loot. Instead, Israel’s forces spring up, strike them, and pursue them into Moab. This scene continues the larger narrative of the Moabite rebellion against Israel and the joint expedition of Israel, Judah, and Edom (earlier in the chapter). Just before this unit, the armies face a life-threatening lack of water, and provision of water is described in a way that sets up what Moab later sees at dawn.
These verses describe a military surprise caused by a visual misunderstanding. Moab mobilizes to meet the invading coalition at the border, but at sunrise they see water that looks red “as blood” and conclude the allied kings have slaughtered each other.
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with 2 Kings 3:22-24, then read the surrounding section so the answer stays connected to the passage's flow.
22They rose up early in the morning, and the sun shone on the water, and the Moabites saw the water over against them as red as blood:
23and they said, This is blood; the kings are surely destroyed, and they have struck each man his fellow: now therefore, Moab, to the spoil.
24When they came to the camp of Israel, the Israelites rose up and struck the Moabites, so that they fled before them; and they went forward into the land smiting the Moabites.