Gunpowder
Gunpowder was an explosive substance that was used, mostly in weapons such as cannons, to explosively propel objects. It was used on Earth and on some primitive planets such as Ribos. (TV: The Ribos Operation)
Gunpowder was developed as an update on the earlier "Greek fire". During the reign of King Richard I of England, when the castle of the English Earl Godfrey was besieged by a gigantic Krynoid, Moses of Tyre of the Knights Templar attempted to reproduce Greek fire from the recipes he had encountered in his years of travel. Instead, by adding charcoal to the mix, he created a new, more explosive substance which blew apart the Krynoid instead of simply burning it. Astounded by the power of Moses's invention, Godfrey resolved to tell the King about it. (AUDIO: The Green Man)
In 1210, the Chin Empire was invaded by the Mongol Empire, providing them with gunpowder. (PROSE: Bunker Soldiers)
In Venice, in the year 1580, Guido detonated a store of gunpowder to destroy a group of Saturnyns. (TV: The Vampires of Venice)
One of the most notable uses of gunpowder was in 1605, where Guy Fawkes and his anti-parliament plotters tried to blow up the Houses of Parliament with several barrels of gunpowder beneath it in what was known as the Gunpowder Plot. (PROSE: The Plotters, GAME: The Gunpowder Plot) The Eleventh Doctor used a few of these barrels to launch a Rutan ship trapped beneath Parliament when he temporarily placed Parliament in Earth orbit. Around the same time, Rory Williams used a cartridge of gunpowder to open a locked door leading to one of the ship's missing power rods. (GAME: The Gunpowder Plot)
While searching through a manor near the Terileptil escape pod, the Fifth Doctor and his companions discovered gunpowder, power packs and the mark of a high energy weapon. The gunpowder was residue from a fight between the owners of the manor and Terileptils. (TV: The Visitation)
In order to fight Windigos, the Eighth Doctor created flash-charges. These were made by adding iron fillings to gunpowder. The light created upon the gunpowder's detonation deterred the Windigos. (COMIC: Bad Blood)
