The attack might have succeeded has it not been for the fact that they unwittingly chose to stage the attack right outside a compartment full of D.A. members, who saw what was happening through the glass and rose as one to rush to Harry’s aid. By the time Ernie Macmillan, Hannah Abbott, Susan Bones, Justin Finch-Fletchley, Anthony Goldstein, and Terry Boot had finished using a wide variety of the hexes and jinxes Harry had taught them, Malfoy, Crabbe, and Goyle resembled nothing so much as three gigantic slugs squeezed into Hogwarts uniforms as Harry, Ernie, and Justin hoisted them into the luggage rack and left them there to ooze.

Harry Potter and the Order of the Phoenix – J.K. Rowling