‘ And Joshua passed from Libnah, and all Israel with him, to Lachish, and encamped against it, and fought against it, And YHWH delivered Lachish into the hand of Israel, and he took it on the second day, and smote it with the edge of the sword, and all the souls who were in it, in accordance with all that he had done to Libnah.'
Lachish was a very large city and put up fierce resistance. But its king was dead and its army decimated. Nevertheless Joshua had to encamp against it before forcing his way past their defences and capturing the city on the second day. But it had no walls sufficient to resist a strong attack, being protected only by its outer layer of houses.