Harry Potter: 7 Times Harry Was A Complete Idiot
6. When He Gave Away His Identity – The Deathly Hallows
Back in The Goblet of Fire, Harry used the Disarming Spell (Expelliarmus) during his first duel with the Dark Lord in the graveyard of Little Hangleton. It was an unusual move to make given the spell doesn’t actually cause any physical harm, and – most importantly – such a move was witnessed by a large group of Death Eaters.
When he uses Expelliarmus during the Battle of the Seven Potters, therefore, those Death Eaters who are pursuing him realise he must be the genuine Harry Potter. Moments later, Voldemort makes an appearance and flys straight up to Harry and Hagrid.
Of course, they manage to escape in the nick of time when they enter the boundary of the Fidelius Charm. But Harry’s use of his signature spell made the trick with the Polyjuice Potion completely redundant, and as a result, he nearly blew the whole operation.