The duel
At some time before 1945, the blood pact was destroyed by unknown means. With the outcry having become too vocal and Grindelwald's actions too horrible for Dumbledore to ignore, he confronted his old friend.
The duel was one of the most well known duels in the world, and one of Dumbledore's most famous moments, with Dumbledore winning the duel and the Elder Wand's allegiance. According to Elphias Doge, eye-witnesses speak of the terror and awe they felt as they watched the extraordinary Dumbledore and Grindelwald do battle, and proclaimed that no duel ever matched theirs.