Many of the battles fought by the children of Israel were internal within themselves. It seemed that they were never satisfied, but murmured against God and Moses. On one such occasion, God sent fiery serpents to bite the complainers and many of the people died from the snake bites.
For an antidote against the bites, God instructed Moses to make a bronze fiery serpent and place it on a pole for the bitten people to look at and be healed. That bronze serpent lifted up in the wilderness was a figure of the Christ who would be lifted up on a cross many years later. Those who look to Christ in obedient faith will be saved from their sins just as the Israelites were saved from physical death by looking upon the bronze fiery serpent.
Kings went out to attack God’s people, but as long as they remained faithful to Him, God would deliver their enemies into their hands.