This has been an argument between a friend and I for a while (the argument mostly centers on the question "does an advance in any/every technology automaticlaly mean an advance in weaponry?"). Is it true that when gunpowder was first discovered in China, it wasn't thought to use it as a weapon, just as a toy/decoration/aesthetic thing?
The very first depiction of gunpowder is as a weapon; once invented, it was almost immediately adapted to military use, and produced in great quantities for military purposes in the forms of rockets and bombs, as well as other weapons. I have a more full answer posted here.