Gunpowder bombs were used again in the 1275 Siege of Changzhou in the latter stages of the Mongol-Song Wars. Upon arriving at the city, Bayan gave the inhabitants an ultimatum: "if you ... resist us ... we shall drain your carcasses of blood and use them for pillows." This didn't work and the city resisted anyway, so the Mongol army bombarded them with fire bombs before storming the walls, after which followed an immense slaughter claiming the lives of a quarter million. The war lasted for only another four years during which some remnants of the Song held up last desperate defenses. In 1277, 250 defenders under Lou Qianxia conducted a suicide bombing and set off a huge iron bomb when it became clear defeat was imminent. Of this, the "History of Song" writes, "the noise was like a tremendous thunderclap, shaking the walls and ground, and the smoke filled up the heavens outside. Many of the troops were startled to death. When the fire was extinguished they went in to see. There were just ashes, not a trace left." So came an end to the Mongol-Song Wars, which saw the deployment of all the gunpowder weapons available to both sides at the time, which for the most part meant gunpowder arrows, bombs, and lances, but in retrospect, another development would overshadow them all, the birth of the gun.