"So Joshua and the whole army moved out to attack Ai. He chose thirty thousand of his best fighting men and sent them out at night with these orders: 'Listen carefully. You are to set an ambush behind the city. Don't go very far from it. All of you be on alert. I and all those with me will advance on the city, and when the men come out against us, as they did before, we will flee from them. They will pursue us until we have lured them away from the city, for they will say, "They are running away from us as they did before." So when we flee from them, you are to rise up from ambush and take the city. The Lord your God will give it into your hand. When you have taken the city, set it on fire. Do what the Lord has commanded. See to it; you have my orders.'" NIV translation
This time, the entire army of Israel went out for the battle. We recall that the first time they had only sent a small force and they had been severely beaten. Now, all of the army is going and they are going with God. This is a picture of the three-stranded cord that King Solomon spoke of (Ecclesiastes 4:12). The same principle applies to our own battle with the flesh in this world. If we try to fight it alone, we will find that our "will power" only goes so far and then we fall again. We also see that, if we have only an army such as a recovery program of some kind and ourselves, we will fall as well. It is only through the presence of God and the encouragement of fellow believers that we are able to stay in the battle until the end and win the war. No retreat, no surrender!