势如破竹

Origin and story

The Book of Jin describes a disagreement during Du Yu's campaign against Wu. Some commanders wanted to wait until winter, fearing approaching heat, flooding, and disease. Du Yu argued that the army had already gained decisive momentum: splitting bamboo becomes easy after the first few joints have opened, because the remaining sections yield to the blade. He urged the advance to continue. The account says cities along the route surrendered and the earlier doubters wrote to acknowledge their mistake. The later idiom condenses this comparison into an image of rapid, successive progress after an initial breakthrough, whether in war or another demanding undertaking.