What does Judges 4:15 mean?

The buildup to this major battle for Israel's independence from Canaan (Judges 4:1–3) is resolved in just two verses. Barak and his troops descend from Mount Tabor to do battle with Sisera's army, including his 900 iron chariots. The Lord goes before Barak's army, and the Canaanites and their chariots are quickly defeated. God's influence is already clear in the victory (Judges 4:7), but there might have been an overtly miraculous aspect to the battle.

Combining details from different verses suggests that Barak's army pulled off a surprise attack on an enemy unexpectedly disabled by a natural disaster. The high ground on Mount Tabor (Judges 4:14) would have been a tactical advantage, yet Barak's men engage Sisera's army on the plain. Further, the Israeli army charges forward on the command of Deborah, the prophetess (Judges 4:4–8). The following chapter suggests a storm or flood swelled the Kishon River, sweeping some of the enemy away. That may also have soaked the field into a muddy mess (Judges 5:19–21). This would have turned iron chariots from a battle advantage into immobile ornaments. In such a situation, Barak's army could have quickly moved through the Canaanites and struck them down. The chariots' only option would be attempting a return to dry ground, effectively retreating, and losing their advantage.

Sisera, realizing the battle would be lost and that his own chariot was useless, got down and ran away on foot. Though it's not likely he traveled completely alone, no other Canaanites are mentioned. He ran northeast from the battle while his remaining soldiers fled back west, the way they had come (Judges 4:16).