The Lord is my Banner

Exodus 17:8-16
Moses built an altar and called it The Lord is my Banner(Jehovahnissi). For hands were lifted up to the throne of the Lord.
Joshua ( the man who will be Moses' successor) leads a picked force against the Amalekites, a nomadic tribe descended from Esau. But it is God who gives the victory, as Moses lifts his hands in prayer.
The Amalekites may have been driving the Israelites away from a fertile oasis.
The record may have been in the lost Book of the Wars of the Lord. After Saul's "holy war" the Amalekites are hardly heard of.
Why?
For Israelite did not have any experience of war, even had not enough sword to fight, their winning is the Lord did for them. So prayer is more important then man's capability. Joshua needs to lead people to fight but the victory is belong to the Lord.
Prayer before any fight or work! God's blessing is essential base.
How?
The Lord is my Banner, through the Prayer to make it.