Global wizarding war

"Gellert - Your point about wizard dominance being FOR THE MUGGLES' OWN GOOD - this, I think, is the crucial point. Yes, we have been given power and, yes, that power gives us the right to rule, but it also gives us responsibilities over the ruled. We must stress this point, it will be the foundation stone upon which we build. Where we are opposed, as we surely will be, this must be the basis of all our counter-arguments. We seize control FOR THE GREATER GOOD."

- Albus Dumbledore to Gellert Grindelwald.

The global wizarding war was a wizarding conflict fought in continental Europe ending in 1945; the common name for which is unknown. It was started by the Dark Wizard Gellert Grindelwald and his followers with the intentions of toppling the European Ministries of Magic, replacing them with a Wizarding Empire that would control the entire wizarding population of Earth and enslave the Muggles for their long ago crimes against wizardkind.

Background and rise to power
"You cannot imagine how his ideas caught me, Harry, inflamed me. Muggles forced into subservience. We wizards triumphant. Grindelwald and I, the glorious young leaders of the revolution."

- Albus Dumbledore to Harry Potter

In the village of Godric's Hollow during the summer of 1899, Albus Dumbledore, who was grieving the loss of his mother, met Gellert Grindelwald, the great nephew of his neighbour Bathilda Bagshot. The two boys took to each other at once, as they were both incredibly talented young men. When the young Grindelwald began telling Dumbledore about his ideas, he found that Dumbledore was in agreement, whether this was due to true belief on Dumbeldore's part or out of something else is unclear. They also believed that wizards have been gifted with their magical powers for a reason, so that they may rule the non-magical population. Grindelwald was forced to leave Godric's Hollow after there was an duel with Dumbledore and his siblings, Aberforth and Ariana in which Ariana died. Some time after leaving Godric's Hollow Grindelwald stole a Deathly Hallow - the Elder Wand from Gregorovitch, a famous wandmaker. Over the coming years, his power grew throughout Europe, but he did not dare attempt anything in Britain as he was afraid of his old friend Dumbledore, who had become a famous and powerful wizard. Due to his obsession with the Deathly Hallows, Grindelwald soon used the symbol as the mark of his own organisation - the army of dark wizards and witches following him and his quest for an international wizard empire.

Fall of Grindelwald
After Grindelwald's rise to power across Europe, the wizarding community desperately sought Dumbledore's aid, because of the latter's reputation as the most powerful wizard of the era. However, Grindelwald was an outstandingly skilled wizard too, and his possession of the Elder Wand further augmented his powers. He constructed Nurmengard, a prison to hold his defeated opponents. It was a fortress protected by magical guards and anti-Apparition wards. Grindelwald's terrorising of Europe went on for years during the Muggle's World War II. Dumbledore knew he had to fight his former friend but kept pushing the moment until "only when it would have been too shameful for him to delay taking action any longer," as Dumbledore said himself. It resulted in a legendary duel between the two great wizards which brought Grindelwald to defeat. Dumbledore claimed the Elder Wand. The Dark Wizard who had terrorized the magical society of continental Europe had fallen. He was ironically imprisoned in his own prison's highest tower where the slogan of Grindelwald was carved above the entrance: "For the Greater Good."

Behind the scenes
J. K. Rowling was asked by a fan if it was a coincidence that Grindelwald was defeated in 1945, to which she replied it was not. She stated "It amuses me to make allusions to things that were happening in the Muggle world, so my feeling would be that while there's a global Muggle war going on, there's also a global wizarding war going on." Rowling also remarked that she feels that Muggle and wizarding wars feed each other.

Appearances

 * Harry Potter and the Philosopher's Stone
 * Harry Potter and the Deathly Hallows