Unity: Joshua begins and ends with concerns about the unity of the tribes. The book expresses a special concern about tribes east of the Jordan River cooperating with those west of the river (1:10–18; 22:7–34). A geographical barrier such as a river often promotes jealousy, regionalism, and civil war; regional customs potentially can distort the worship of the Lord. Success in the battle for Canaan depends on fielding forces from both the east and the west. That unity depends on loyalty first to Moses and now to Joshua.

Judges chronicles the breakdown of tribal unity. The outrage at Gibeah and the civil war against Benjamin (Judg. 19–21) demonstrate why Joshua was concerned about unity. Joshua’s farewell address (23:6–16) and the covenant renewal ceremony (24:15–24) emphasize the importance…