To take Kuju, Saritai used a full array of siege weapons to bring down the city's defenses. Lines of catapults launched both boulders and molten metals at the city's walls. The Mongols deployed special assault teams who manned siege towers and scaling ladders. Other tactics used were pushing flaming carts against the city's wooden gates and tunneling under the walls. The most grisly weapon used during the siege were fire-bombs which contained boiled down, liquefied human fat. Despite the fact the Goryeo army was heavily outnumbered and after over thirty days of brutal siege warfare, Goryeo soldiers still refused to surrender and with mounting Mongol casualties, the Mongol army could not take the city and had to withdraw.