When Harry Potter went back to Hogwarts toward the end of what would be his seventh year to find the Horcrux Voldemort had hidden there, Voldemort was trying to find all the Horcruxes. He knew where Harry was and initiated the Battle of Hogwarts, but instead of giving Harry up, the students and teachers kept fighting to protect him, but to stop the fighting, Harry went to give himself up. The Killing Curse didn't work, but it did destroy the Horcrux inside of Harry. Towards the end, Neville Longbottom (Now Herbology Professor at Hogwarts) destroyed the last Horcrux and Voldemort's disingrated into nothing.