To the upper right we have very pure potassium chlorate, so much so that it bursts into flames when mixed with sugar and catalyzed with some sulfuric acid. [Mr. Home Scientist] produced the KClO3 ...

I wonder if they were trying to make shaped charges or just placing omnidirectional explosives in strategic locations (or even artificially creating confinement). Brass was better (and more expensive) ...

First used for battle in China in about 900 A.D., gunpowder spread throughout Eurasia by the end of the 13th century, eventually revolutionizing warfare as a propellant in firearms and artillery.