Draco Disarms Dumbledore

The door burst open and somebody erupted through it and shouted, “Expelliarmus!”

Harry’s body became instantly rigid and immobile, and he felt himself fall back against the tower wall, propped like an
unsteady statue, unable to move or speak. He could not understand how it had happened — Expelliarmus was not a Freezing Charm —

Then, by the light of the Mark, he saw Dumbledore’s wand flying in an arc over the edge of the ramparts and understood. . . Dumbledore had wordlessly immobilized Harry, and the second he had taken to perform the spell had cost him the chance of defending himself.

Chapter 27-The Lightning-Struck Tower