Be Strong - Joshua - WBS by Warren W Wiersbe and published by David C Cook.
God isn't looking for volunteers, because every Christian is a soldier in the army of the Lord. Some are "good soldiers of Jesus Christ" while others are AWOL or casualties on the battlefield of life. Joshua was one of God's early soldiers on the winning side. Thrust into leadership when Moses died, Joshua took to heart God's instructions about the keys to victory. Putting fear aside and realizing the Lord was his true source of strength, Joshua became God's instrument for bringing the Israelites safely into the Promised Land.