<P> On the first night while laying siege to a city, the leader of the Mongol forces would lead from a white tent: if the city surrendered, all would be spared . On the second day, he would use a red tent: if the city surrendered, the men would all be killed, but the rest would be spared . On the third day, he would use a black tent: no quarter would be given . </P> <P> However, the Chinese were not completely defenseless, and from AD 1234 until 1279, the Southern Song Chinese held out against the enormous barrage of Mongol attacks . Much of this success in defense lay in the world's first use of gunpowder (i.e. with early flamethrowers, grenades, firearms, cannons, and land mines) to fight back against the Khitans, the Tanguts, the Jurchens, and then the Mongols . </P> <P> The Chinese of the Song period also discovered the explosive potential of packing hollowed cannonball shells with gunpowder . Written later around 1350 in the Huo Long Jing, this manuscript of Jiao Yu recorded an earlier Song - era cast - iron cannon known as the' flying - cloud thunderclap eruptor' (fei yun pi - li pao). The manuscript stated that (Wade--Giles spelling): </P> <P> The shells (phao) are made of cast iron, as large as a bowl and shaped like a ball . Inside they contain half a pound of' magic' gunpowder (shen huo). They are sent flying towards the enemy camp from an eruptor (mu phao); and when they get there a sound like a thunder - clap is heard, and flashes of light appear . If ten of these shells are fired successfully into the enemy camp, the whole place will be set ablaze...</P>

Where did the decisive early encounters of the civil war take place