We know Frank and Alice were purebloods, prominent Aurors, and members of the Order of the Phoenix. We know that Neville was the other candidate for the prophecy because Frank and Alice thrice defied Voldemort. We also know that a group of Death Eaters including Bellatrix Lestrange and Barty Crouch, Jr. attacked them and cruciated them to insanity while trying to find information on Voldemort's whereabouts after his attack on the Potters. We don't really know much else.


I'm wondering if we have a definitive date for when the Death Eaters attacked them, or if it's all speculation. It isn't really all that important in the grand scheme of things, but Ive got a semi-plot going on in my head, and it might be helpful.

 

I can only assume that the attack came fairly soon after Voldemort's fall since his support was crumbling and his minions were being rounded up without his leadership.

I doubt that a small Death Eater cell like the one that attacked the Longbottoms could have operated very long on its own, especially given the prominence of its members.

 

Short answer: never specified, no clue.

It's always something I've wondered as well. It's fun to speculate how it went down; that is, did they each, individually, defy Voldemort 3x? Did they do it as a couple? Did it happen as a group (the Potters and the Longbottoms, on a mission for the Order, perhaps)? Did any of the attacks occur during Hogwarts? Were the defiances even attacks? Example:

Voldemort: Knock Knock
Longbottoms: Who's there?
V: Voldemort. Join me.
L: Dun wanna.
V:...that's 1, fuckers.

~Three days later @ the Potters~
Voldemort: Knock Knock...

Lame example, but the point is that there are so many ways to 'defy' someone, whether directly or indirectly.