24 Harry Potter Easter Eggs And Details You Probably Missed
15. The Mysteriously Broken Vanishing Cabinet
In The Chamber Of Secrets, Nearly Headless Nick convinces Peeves to drop the Vanishing Cabinet above Filch's office in order to distract him from catching Harry. If it wasn't dropped, it wouldn't have needed repaired (obviously) therefore the final battle would have happened much sooner, probably before the students of Hogwarts could defend themselves. So it seems that Rowling's plan was always for the Death Eaters to enter Hogwarts this way.