Which, all things considered, is probably where the term Sally Forth came from to indicate a force going forth to cause havoc.
Unlike, as one character asked, Hoist by their own Petard, which is from one of the earlier 'oops' of pyrotechnic warfare.
Way back in the day, a mortar wasn't the thin tube shaped thing we know of today. What it was, was a very thick walled cannon, with a short - very short - barrel aimed well above 45 degrees off of horizontal. And originally, it was called a: You guessed it, a Petard.
Now, to fire it off, you touched a touch hole much like any other cannon.
To make sure the shell went off though, you had to light a fuse that was on the top of the shell inside the gun tube by reaching in with a lit length of slow match.
Trick is, you had to do *both* at the same time, and hope you got the propellent charge the first time - as there wasn't any time to try again because you *had* to assume that you got the shells fuse lit.
You can imagine I am sure the results of lighting the shell off whilst it was still in the tube.
Hence: Hoist (As in blown up) by your own Petard. :)
