with gunpowder have been used in warfare since at least early 13th century China. Hollow, gunpowder-packed shells made of cast iron used during the Song dynasty (960-1279) are described in the early Ming Dynasty Chinese military manual Huolongjing, written in the mid 14th century. The History of Jin 《金史》 (compiled by 1345) states that in 1232, as the Mongol general Subutai (1176–1248) descended on the Jin stronghold of Kaifeng, the defenders had a "thunder crash bomb" which "consisted of gunpowder put into an iron container ... then when the fuse was lit (and the projectile shot off) there was a great explosion the noise whereof was like thunder, audible for more than thirty miles, and the vegetation was scorched and blasted by the heat over an area of more than half a mou. When hit, even iron armour was quite pierced through." Archeological examples of these shells from the 13th century Mongol invasions of Japan have been recovered from a shipwreck. Shells were used in combat by the Republic of Venice at Jadra in 1376. Shells with fuses were used at the 1421 siege of St Boniface in Corsica. These were two hollowed hemispheres of stone or bronze held together by an iron hoop. At least since the 16th century grenades made of ceramics or glass were in use in Central Europe. A hoard of several hundred ceramic grenades dated to the 17th century was discovered during building works in front of a bastion of the Bavarian city of Ingolstadt, Germany. Many of the grenades contained their original black-powder loads and igniters. Most probably the grenades were intentionally dumped in the moat of the bastion before the year 1723. An early problem was that there was no means of precisely measuring the time to detonation reliable fuses did not yet exist, and the burning time of the powder fuse was subject to considerable trial and error. Early powder-burning fuses had to be loaded fuse down to be ignited by firing or a portfire or slow match put down the barrel to light the fuse. Other shells were wrapped in bitumen cloth, which would ignite during the firing and in turn ignite a powder fuse. Nevertheless, shells came into regular use in the 16th century, for example, a 1543 English mortar shell was filled with "wildfire." By the 18th century, it was known that the fuse toward the muzzle could be