Back in Genesis 9, we read about Canaan being cursed because his father, Ham, dishonored Noah. Here we see a Canaanite city being completely destroyed. Israel also defeats the Amorites and Bashan. However, in the midst of these battles, Israel is punished for complaining by being bitten by snakes. The only cure is to look at a bronze snake.
The story of the bronze snake is mentioned in John 3:14, just before the most famous verse in the Bible. It is pointed out that both the bronze snake and Jesus were lifted up on wooden poles. The people of Israel needed to look to the bronze snake for healing, and today, we need to look to Jesus for forgiveness of our sin.