2 Samuel 20:15

They came and besieged him Joab and his army pursued him thither. And cast up a bank They raised a very large mound of earth, equal, probably, to the height of the walls, from whence they might either batter the walls, or throw darts, or shoot at those that defended them. It stood in the trench This bank or mound was carried on so far, that it now stood in or near to the trench and foot of the wall; so that the city was in great danger of being taken.