Albert Barnes Commentary Judges 5:20

"From heaven fought the stars, From their courses they fought against Sisera." — Judges 5:20 (ASV)

God fought on the side of Israel, and gave them the victory. Josephus relates that, just as the battle began, a violent tempest arose with a great downpour of rain; and a hailstorm, which, driving directly into the faces of the Canaanites, so blinded and numbed them with cold, that they could neither use their bows effectively nor even hold their swords.