2 Samuel 10:14

So Joab returned. It seems strange to us that Joab should have made no attempt to follow up his victory. But as the Ammonites were posted close to the gate of their city, they would withdraw into it without less as soon as they learned that their allies were defeated. There was thus the certainty of a long siege before Rabbah could be taken. We gather from 2 Samuel 11:1 that it was late in the year when Joab won this victory, and it was part of the weakness of ancient warfare that a long campaign was beyond the power of either side.