V.1-2 – GOD instructs Joshua to do battle with Ai once more; this time, however, the situation will be different: 1) rather than a token force (like last time in chapter 7), all of Israel’s soldiers will be brought to bear; 2) the Israelites are permitted to take spoil for themselves from their conquest (only property, no people); 3) GOD is with them in this battle, and has assured Joshua of victory; and 4) GOD has instructed Joshua on what strategy to use.
V.3-8 – Following GOD’s instructions, Joshua sets aside a group of soldiers (30,000) to wait in ambush behind Ai’s location; Israel is going to use a feint with their main force to draw Ai’s army away from the city. Once that is done, the ambush force will attack the city, descend the hill, and attack the army of Ai from the rear while Israel’s main force turns back and engages them from the front.
V.9-13 – The ambush is set up during the night, and Joshua sends out a third force (5,000) to prevent the neighboring city-state from sending forces to assist Ai. The next day, Joshua leads the main force in the feint maneuver: 1) They make camp in the valley below the city, where they can be easily seen, and will appear to be an attractive lure for Ai, 2) the two ambush forces settle into position, undetected, 3) at daybreak, the battle is set to begin.
V.14-20 – The soldiers of Ai are drawn into the trap; they are so convinced of victory that no one stays behind to defend Ai. As they come rushing out, Joshua and the main attack force pull back (feigned retreat) to put some distance between the soldiers and their now-defenseless city. When Joshua gives the signal (waving his spear, possibly with a flag or another way to distinguish himself in the midst of battle), Israel’s main army turns around to attack Ai, and the larger ambush force charges into the city, putting it to the torch.
V.21-29 – With the ambush complete, Israel’s forces turn and complete annihilate Ai’s population (12,000 total); the livestock and wealth of the city (from hereon forward) is divided among the Israelites. As a note of interest, the Israelites have (not yet) taken no captives (Rahab and her family do not count as such, since they were integrated as members of the nation). There are two commands of GOD regarding this matter: 1) to Israel (found in the Pentateuch) and 2) to Joshua personally (the beginning of chapter 8). When captives are taken, Israel is to treat them gently and with respect. Israel has been the oppressed; they should NOT become the new oppressor.
V. 30-35 – Following Moses’ precedent, Joshua leads the people in worship after the battle is finished; GOD is the crucial part of Israel’s victories, and Joshua (having learned this lesson in the wilderness) is keen on making sure the next generation remembers it well. Additionally, Joshua copies the Mosaic Law onto the stones of the altar he has built; it is both an instructional tool and a reminder that the Law is Israel’s covenant pact with GOD, applying to every member of the nation.