How did Voldemort become so much more powerful when he came back the second time?

Question

After Voldemort's disappearance, some wizards secretly stayed allied to him (as seen in Goblet of Fire when they immediately come to him after he returns in the graveyard). There were very few, however, that showed up. Some more were broken out of Azkaban the following year, but it couldn't have been more than a handful of faithful supporters.

Then, with this limited number of followers, within 3 years Voldemort manages to have people allied to his cause in some of the highest positions in the wizarding community, including:

• Headteacher of Hogwarts (or so he thought)
• Head of Magical Law Enforcement
• Minister of Magic (pretty much the highest position a wizard/witch can have as far as I know)

This is not including the vast number of his followers that worked under these people, or were working to further his cause anywhere else (other teachers, snatchers, others within the ministry etc.).

So how did he manage to garner so much support so quickly, and in such influential positions within the wizarding infrastructure?

Was he even nearly this powerful the first time that he was around?

Answer 1

There are several reasons:

1. The secrecy surrounding his rebirth.

   Fudge spends most of Order of the Phoenix denying Voldemort's return, and by extension, so does the rest of the Ministry. He actively suppresses any news about Voldemort, even Dumbledore's comments on the matter:

   “While the Ministry insists there is nothing to fear from Voldemort, it’s hard to convince people he’s back, especially as they really don’t want to believe it in the first place. What’s more, the Ministry’s leaning heavily on the Daily Prophet not to report any of what they’re calling Dumbledore’s rumour-mongering, so most of the Wizarding community are completely unaware anything’s happened, and that makes them easy targets for the Death Eaters if they’re using the Imperius Curse.”

   — Order of the Phoenix, chapter 5 (The Order of the Phoenix)

   This gives Voldemort time to work quietly in the background – recruiting followers, sending envoys to the giants, quietly silencing minor enemies – with relative impunity. By the time Fudge realises that he's returned, he's built up a significant foothold.

   The wizarding community is small and fragmented. Individual families are easy pickings.

2. The Ministry has a reduced number of Aurors.

   Voldemort killed a large chunk of the magical population during his first reign of terror. That included a lot of Aurors or would-be Aurors. As a result, the Ministry will have a much smaller group of Aurors around the time of Goblet of Fire.

   Even if they wanted to, the Ministry would struggle to track Voldemort's progress (they don't; they're busy chasing Sirius), and less Aurors mean they're less likely to spot other signs of his return.

   (According to the HP Wikia, Tonks was the last Auror to qualify before Harry, and she qualified sometime in Goblet of Fire. I think I've seen the source, but I can't find it now.)

3. He already had loyal servants in high places.

   When he first rose to power, he had to build a network of Death Eaters and contacts. When he returns, he already has people like Lucius Malfoy and Snape, who are installed and influential in society. He'll be able to use their positions to get access to other important people – a foothold he didn't have the first time.

Finally, it's worth remembering that Voldemort nearly won the First Wizarding War. He had completely infiltrated the Ministry, decimated any form of resistance, and had most of the community terrified. It was a lucky fluke that he was defeated. Many people are still scared from the first war – this is a much easier population to conquer.

Answer 2

He had a year in which almost nobody believed he existed.

The time he gained by Fudge's stupidity during HP and the Order of the Phoenix must have been immensely valuable. Time when he could make his plans - and bring plans to fruition that he must have been making all through his years in a half-dead state - while the only enemies he had to deal with were the Order of the Phoenix, who also had to act in secret and deal with oppression from the Ministry. Time during which his agents within the Ministry, people like Lucius Malfoy who were above suspicion, could manoeuvre affairs into a position favourable for Voldemort.

In his first rise to power, he never had such a perfect opportunity. Sure, there was a time when most people didn't realise how dangerous he was, but they always knew he existed. Being a non-entity can be a very powerful position to be in, from the point of view of making secret plans.

By the time the Ministry were willing to accept Voldemort was back and a force to be reckoned with, enough of his schemes were in place that he was able to topple them within little more than a year (between the end of HP and the Order of the Phoenix and the start of HP and the Deathly Hallows).

Answer 3

His previous allies have matured, were exonerated or considered under imperious and had taken respectable positions within society and had developed allies within the ministry. He and his allies have been scheming ever since his return was revealed. When he came back in physical it was more like flipping a switch to finish the job of taking over, first by proxy through his allies and then finally in fact when he had enough support within the ministry to put his own people in there directly.