Did the remaining Death Eaters fight back after Voldemort's death?

Question

After Voldemort died, shouldn't the remaining Death Eaters still fight back? We know that they don't need a leader to organize their attacks:

Loud jeering, roars of laughter, and drunken yells were drifting toward them; then came a burst of strong green light, which illuminated the scene. A crowd of wizards, tightly packed and moving together with wands pointing straight upward, was marching slowly across the field. Harry squinted at them... They didn’t seem to have faces... Then he realized that their heads were hooded and their faces masked.

^{Harry Potter and the Goblet of Fire}

We also know that they have presumed Voldemort dead, before:

Some say he died.

^{Hagrid -- Harry Potter and the Sorcerer's Stone}

I can't find an exact quote at the moment, but we also know that some Death Eaters came running back to the Ministry under the pretense of remorse because they believe Voldemort dead.

---

My question is: Did the Death Eaters ever attack the "good" side after the end of the Battle of Hogwarts, and, if not, why?

Answer 1

No, they had too few for large-scale attack.

Though it’s possible that some individual Death Eaters may still have attacked the “good” side, after the war, there weren’t many Death Eaters left for them to make any sort of large-scale resurgence after the war. The number of Death Eaters who were available and willing to attack without the Dark Lord’s protection was severely diminished from the number of Death Eaters who were active during the height of the war. Many had been killed in the war, others were fleeing to avoid imprisonment, and some were being captured.

“He must speak to the bereaved, clasp their hands, witness their tears, receive their thanks, hear the news now creeping in from every quarter, as the morning drew on, that the Imperiused up and down the country had come back to themselves, that Death Eaters were fleeing or else being captured, that the innocent of Azkaban were being released at that very moment, and that Kingsley Shacklebolt had been named temporary Minister for Magic …”
_{^{- Harry Potter and the Deathly Hallows, Chapter 36 (The Flaw in the Plan)}}

The Death Eaters didn’t attack again as a group after the Dark Lord’s fall because they wouldn’t have had the chance or the ability to. The Death Eaters who were fleeing wouldn’t have wanted to attack again because they’d almost certainly get caught, and any who wanted to deny their involvement also wouldn’t want to risk attacking. The ones who were being captured may have attempted attacking before their capture, but were caught soon after, so while they may have tried, they wouldn’t have been particularly successful. Then, once they were caught, they’d be sentenced and imprisoned, so they’d no longer be able to attack unless they escaped from Azkaban.

But individual or a few Death Eaters may have.

Although the number of willing Death Eaters was severely diminished making a large-scale attack impossible, there’s no evidence that individual Death Eaters, or groups of a determined few, never attacked anyone on the other side after the war. Though we know nineteen years after the war, at the time of the epilogue, “all was well”, that doesn’t eliminate the possibility of there being a few Death Eaters that attacked people before then. For example, after the first war was over and the Dark Lord fell from power, Bellatrix and a few other Death Eaters attacked the Longbottoms.

“The Longbottoms were very popular,’ said Dumbledore. ‘The attacks on them came after Voldemort’s fall from power, just when everyone thought they were safe. Those attacks caused a wave of fury such as I have never known. The Ministry was under great pressure to catch those who had done it. Unfortunately, the Longbottoms’ evidence was – given their condition – none too reliable.”
_{^{- Harry Potter and the Goblet of Fire, Chapter 30 (The Pensieve)}}

Though they were in theory attempting to get information on where the Dark Lord could be, they also wanted to torture Aurors, which would still be a possible motivation for Death Eaters even after the Dark Lord was known for sure to be dead.

SU: Oh, that's so cool. Can we just ask kind of a sad thing, though. What did the Longbottoms do that they earned that wrath from Bellatrix? Such-- There's three times, like the Potters thrice defied the Dark Lord.

JKR: They were efficient! They were efficient. That's all they needed to do to earn her wrath. They were-- They had rounded up Death Eaters, they were very good Aurors, they knew what they were doing, they were responsible for a lot of captures and arrests and imprisonments. And-- So there you are.
_{^{[- PotterCast Interviews J.K. Rowling, part 1 (December 17, 2007)][1]}}

There also may have been some individual Death Eaters who attempted to attack, since some of them enjoyed torturing and may not have been willing to simply flee.

“There was Antonin Dolohov,’ he said. ‘I – I saw him torture countless Muggles and – and non-supporters of the Dark Lord.”
_{^{- Harry Potter and the Goblet of Fire, Chapter 30 (The Pensieve)}}

Therefore, despite the low numbers of Death Eaters making it impossible for them to truly have a resurgence and the knowledge that nineteen years later all was well, it’s still possible that there were some Death Eaters who attacked after the war.

Answer 2

There are several points to consider here. First, the book ends basically right after Voldemort dies, so any attacks by Death Eaters after this wouldn't be covered. Additionally, the epilogue concludes as follows:

The scar had not pained Harry for nineteen years. All was well.

This could imply that there were no further difficulties with Death Eaters after Voldemort was killed.

Another point is that there weren't many Death Eaters left to mount an attack. As stated in Chapter Thirty-Six of Deathly Hallows (my emphasis):

He must speak to the bereaved, clasp their hands, witness their tears, receive their thanks, hear the news now creeping in from every quarter as the morning drew on; that the Imperiused up and down the country had come back to themselves, that Death Eaters were fleeing or else being captured, that the innocent of Azkaban were being released at that very moment, and that Kingsley Shacklebolt had been named temporary Minister of Magic.

If the Death Eaters were either captured or gone, there wouldn't be anyone to initiate any attacks.

More fundamentally, we have to consider why Death Eaters would attack. We know that after Voldemort's initial defeat many Death Eaters "came back" to the good side. Even someone like Lucius Malfoy who fully agreed with Voldemort's agenda did not dare stir up trouble without Voldemort around. It was simply not worth it to oppose the Ministry and the rest of the Wizarding World without the power of Voldemort behind you. This would be even more true for those Death Eaters who weren't as devoted to Voldemort's goals in the first place.

As for the situation at the Quidditch World Cup, we can surmise that that was somewhat unique. First of all, the Death Eaters didn't openly attack other wizards; they were merely having fun with some Muggles. There wasn't that much of a risk involved, as they could just disapparate as soon as anyone from the Ministry got too close, since they weren't trying to fight other wizards anyway. And perhaps most importantly, this took place shortly after Wormtail had helped restore Voldemort to some semblance of physical existence, with a plan in motion to bring him back to full power. It is likely that the Dark Mark had already begun to grow stronger, as Voldemort came closer to regaining his full power. As Snape said in Chapter Thirty-Six of Goblet of Fire:

This Mark has been growing clearer all year.

This being the case, it might have occurred to them that Voldemort might soon be returning. This might give them the confidence to return to their Death Eater activities.