What was Big Willy Shakes going for?
Margaret predicts that people who stand too tall over everybody else will soon "dash to pieces." Basically, she wants them to break. Hard. It's pretty clear that Margaret wants the worst for these peeps. Let's answer the question on everybody's minds: what's Margaret so bitter about?
Well, for one thing, Queen Margaret's late husband was bumped off the throne by Richard's family so that Edward IV could be crowned king. Richard also killed her son, so she's pretty unhappy about that. Oh, and did we mention that since Margaret is a woman and a widow, her livelihood depends on the people who murdered her husband and son? In other words, Margaret was once a queen but now she's a charity case without a husband or a son, relying on the very people who ruined her life. Needless to say, she's angry about it.
The grief she feels is awful, and the fact that the murders have gone unavenged only adds insult to injury. Worse than anything, Margaret feels irrelevant, and her unnoticed misery only fuels her wrath. Before we start feeling too sorry for Margaret, thought, we should keep in mind that our girl has done some pretty nasty things, too. Check out the Henry VI plays if you want to know more.
So now we understand why she's mad. Let's think about how she declares it. Margaret uses the word "dash" in the sense that something will fall and break violently. She's going for the image of something smashing to pieces. Not the nicest image of someone falling. But hey, Margaret doesn't care if her enemies go Humpty-Dumpty on her.
Before Margaret said "dash to pieces" the closest anyone had come to saying it was the Bible. In 1535, the Coverdale Bible had "break them in pieces" but it wasn't quite as catchy as Shakespeare's version from 1592 (in this play). It looks like Margaret's little phrase caught on and fast. Before long, Shakespeare used it in some other plays, including The Tempest, Julius Caesar, and Henry IV, Part II.