Military activities in the Middle East generally started in the spring, after the end of the winter rains, and this was when the Israelite troops under Joab were dispatched in the continuation of the siege to Rabbah (from the last chapter, while David stayed behind (cf. 2 Samuel 10:7–14). This turns to be the setting for David's downfall: providing him with an opportunity to see Bathsheba bathing and then to commit adultery with her.
