In the story, 1945, Grindelwald was defeated by Dumbledore and imprisoned in the tallest tower in Neumengarde. It is said that he showed remorse in his later years. Harry heard about Grindelwald through the chocolate frog card, and heard something about Grindelwald from Victor krum at Bill and Furong's wedding. Krum said Grindelwald killed his grandfather.
1998, Voldemort sneaked into Newgate and forced him to ask the whereabouts of the elder's wand. In order to prevent the tomb of his ex-lover Dumbledore from being destroyed, Grindelwald lied that he never got it, mocked Voldemort and was later killed.
Character background
Around 1926, Grindelwald and his followers launched many terrorist attacks in Europe, which made people panic for a time, and Hogwarts School of Witchcraft and Wizardry also increased its security.
1926, Grindelwald pretended to be Auror percival Grievous and entered the American Magic Conference, trying to find a silent man with the help of a boy whose life was a mystery. However, in the end, he found that Claudens was the silent one. Claydens broke out silently in his body, which was shattered (not dead) by Auror after the mass destruction of new york, and his own identity was exposed by Newt Scarmand. Grindelwald was put in prison.