Coming to grief

I’ve been taken down a peg or two – in my own arrogant estimation, thinking that I’m almost an expert in English and its vocabulary, idioms and variations. I have actually just googled my opening phrase and leaned something I might have guessed at but didn’t actually know:

Just to sidetrack, with being taken down a peg or two, well, it’s an eighteenth century British naval expression indicating the seniority of a ship shown by how high its flags, or more correctly its colours, were flying. They were raised and, lowered by a system of pegs, the higher the peg holding the flag, the higher the ship’s status.

I’d heard, and used the phrase ‘hoist by your own petard’, on countless occasion, and I thought, that like being taken down a peg or two it came from a naval expression, and that a petard was a flag which would be raised or hoisted and therefore a signal well and truly made. Well silly old me – as you might be thinking right now. because a petard isn’t a flag at all! A petard is a small bomb which was a metal or wooden box filled with gunpowder and used as an explosive to blast down a door or wall. Being hoist by your own petard means coming to grief by your own actions.

So, I have been taken down a peg or two, by not knowing the correct origin of the phrase ‘hoist with your own petard’. It’s probably no surprise that the phrase comes from Shakespeare, from Hamlet himself describing how he has planned to have Rosencrantz and Guildenstern dispatched by the King of England and not Hamlet: “’tis the sport to have the engineer hoist with his own petard.”