How Were the Death Eaters Broken Out of Azkaban?

Question

How were the Death Eaters broken out from Azkaban in Order of the Phoenix?

From the Daily Prophet:

‘We find ourselves, most unfortunately, in the same position we were two and a half years ago when the murderer Sirius Black escaped,’ said Fudge last night. ‘Nor do we think the two breakouts are unrelated. An escape of this magnitude suggests outside help, and we must remember that Black, as the first person ever to break out of Azkaban, would be ideally placed to help others follow in his footsteps.

_{Order of the Phoenix - page 481 - Bloomsbury - chapter 25, The Beetle at Bay}

AND

Samantha: Was Snape the only Death Eater who could produce a full Patronus?

J.K. Rowling: Yes, because a Patronus is used against things that the Death Eaters generally generate, or fight alongside. They would not need Patronuses.

_{J.K. ROWLING - WEBCHAT 07.30.07 - THE LEAKY CAULDRON}

I'm going to guess Voldemort did not break out the nine Death Eaters himself -- it's not his style to do the dirty work. I'll further guess that it's possible a group of Death Eaters who were not incarcerated was sent to break the nine out of Azkaban. Assuming this scenario is basically possible and accurate, how were the Death Eaters broken out of Azkaban, in light of the fact that 1) Azkaban is rumored to be Unplottable¹ and 2) Death Eaters cannot produce Patronuses, and at the time of the break-out the Dementors were still under the control of the Ministry?

I'd like a canon-based answer, such as from the books, J.K. Rowling interviews, or Pottermore.

¹_{I cannot find verification that Azkaban is Unplottable in any of the J.K. Rowling interviews I have bookmarked or in canon. The HP Wikia says Azkaban is Unplottable, but I would prefer canon verification. I'm sure I've heard that Azkaban is Unplottable before, from another source, but I just cannot find it this morning! On the other hand, if Azkaban is Unplottable, how would any Death Eater know how to get there to facilitate a break in to begin with?}

Answer 1

The key to this question is in your statement: "at the time of the break-out the Dementors were still under the control of the Ministry." Were they?

Remember, Dementors served whomever they felt like serving. They worked for the Ministry since they were guaranteed to continue their existence by feeding off the misery innate within Azkaban's walls. They are first and foremost Dark creatures, and they definitely were not bound to the Ministry. As Voldemort told his followers, the Dementors are his "natural allies."

Additionally, this wouldn't have been the first dereliction of duty from the Dementors that year. Earlier in the year, they had attacked Harry and Dudley in Little Whinging, as seen in Chapter 1 of Order of the Phoenix.

As Dumbledore said:

‘If it is true that the Dementors are taking orders only from the Ministry of Magic, and it is also true that two Dementors attacked Harry and his cousin a week ago, then it follows logically that somebody at the Ministry might have ordered the attacks,’ said Dumbledore politely. ‘Of course, these particular Dementors may have been outside Ministry control –’
‘There are no Dementors outside Ministry control!’ snapped Fudge, who had turned brick red.

I believe they felt Voldemort's return, a "disturbance in the Force," so to speak. If they were not yet in contact with him, they probably knew he was back. They go where the misery goes, so to speak. They facilitated the DE escape from Azkaban, in order to set loose more misery elsewhere.

Hermione echoes this suspicion, when she reads the Ministry's claim that Black helped them escape:

‘I don’t believe this,’ snarled Harry, ‘Fudge is blaming the breakout on Sirius?’
‘What other options does he have?’ said Hermione bitterly. ‘He can hardly say, “Sorry, everyone, Dumbledore warned me this might happen, the Azkaban guards have joined Lord Voldemort” – stop whimpering, Ron – “and now Voldemort’s worst supporters have broken out, too.” I mean, he’s spent a good six months telling everyone you and Dumbledore are liars, hasn’t he?’