Bible Verses About Sieges: Frequently helped by allies

On the next day, Saul put the people in three companies; and they came into the midst of the camp in the morning watch, and struck the Ammonites until the heat of the day. Those who remained were scattered, so that no two of them were left together.

David and his men went to Keilah, and fought with the Philistines, and brought away their livestock, and killed them with a great slaughter. So David saved the inhabitants of Keilah.