This might sound like speculation, but can it be reliably predicted from canon what Voldemort would have done after he won, were he successful in defeating Harry and the Order?
Would he just rule over the wizard world and keep up the masquerade, or would he try to take over the whole Earth by starting a (dark-)wizard vs. muggle war?
He wouldn't have been content with simply ruling the Wizarding world. Voldemort hated his father for being a Muggle and no doubt resented being a half-blood wizard despite also being the Heir of Slytherin; he even went as far as to adopt a new name to disguise the fact he was related to a Muggle family.
I think the new statue in the Ministry of Magic when Voldemort has (secretly) assumed control gives a pretty clear indication of his thoughts about Muggles and what he would have done with them if he'd had free reign to do so:
Now a gigantic statue of black stone dominated the scene. It was rather frightening, this vast sculpture of a witch and a wizard sitting on ornately carved thrones, looking down at the Ministry workers toppling out of fireplaces below them. Engraved in foot-high letters at the base of the statue were the words MAGIC IS MIGHT.
...
Harry looked more closely and realised that what he had thought were decoratively carved thrones were actually mounds of carved humans: hundreds and hundreds of naked bodies, men, women and children, all with rather stupid, ugly faces, twisted and pressed together to support the weight of the handsomely robed wizards.
"Muggles," whispered Hermione, "In their rightful place. Come on, let's get going."Deathly Hallows - Chapter 12, Magic is Might
I hate to tell you, but he did win. For all intents and purposes, during the majority of Book 7, Voldemort won. Sure there was some resistance, but... What did he do?
I'm sure there's quite a bit more that could be added, but you get the idea. I really doubt Voldemort even cared that Harry Potter was running around, at least not that much...
We saw Voldemort getting started on this in Deathly Hallows, of course, with Muggleborn registration and purges of those disloyal to him.
However, as of Harry Potter and the Cursed Child, we actually have a very good idea of what the end state would have been.
In Harry Potter and the Cursed Child, the actions of Albus Severus Potter and Scorpius Malfoy created an alternate timeline in which Voldemort won the Battle of Hogwarts, and the fight against the Order generally.
He would have let dementors breed freely and infest everywhere with despair.
UMBRIDGE: I don’t know what game you’re playing but you’re upsetting the dementors and entirely ruining Voldemort Day.
He would have made holidays in his name, and otherwise behaved pompously. Children woul have been taught to venerate Voldemort.
He would not have openly ruled over Muggles, at least not on anything like an immediate timescale, perhaps fearing retribution from other magical governments if the Statute of Secrecy were broken. Violence against Muggles, properly explained away, would become a frequent occurence, however.
DRACO: And no, those idiots blasting Muggles, that’s not my doing, though it’ll be me the Augurey asks to bribe the Muggle Prime Minister with gold....
If Voldemort were ruling over the Muggles, there would be no need to propitiate any Muggle government officials.
Muggleborns would have been treated like slaves and vermin, tortured, put into death camps, and otherwise ill-treated:
SCORPIUS: The “Mudblood” death camps, the torture, the burning alive of those that oppose him.
He didn't rule the wizarding world, he simply ruled the wizarding community of Great Britain. He would have to fight and take down not only The International Confederation of Wizards, but also EVERY SINGLE MAGICAL GOVERNMENT in the entire world! That wouldn't be an easy thing to do, not even for a wizard as powerful as Voldemort. The British Ministry of Magic be a very resourceful tool, but if you think about it, he couldn't even THINK about starting to take over other parts of the world if he crushed the resistance from what was left of the Order of the Phoenix.
Send a handful of Death Eaters into the United States, but don't expect the wizarding government, (which I like to call the U.S. Department of Magical Affairs) to sit by and watch the Death Eaters attack them. There would be a bloodbath, because they wouldn't put up with an attack from England, be it Ministry of Magic controlled by Voldemort or not. Unless Voldemort gathered A LOT more followers and extended his army to about, what, ten times the size, he wouldn't dare attack any other nation, because they would step on him like a bug, especially if they were to receive assistance from another country as well. Voldemort was known all over the world, and I can easily imagine that there are MANY from Europe and USA who would be willing to fight him.
I think Voldemort would have repeated the strategy which he used to take over the Ministry of Magic, to take over all the magic governments in the world. After that, he would have focused his attention on the Muggle governments. I don't think they would have seen it coming.
And then, he would have shown himself, as the ruler of the world -- maybe for all time. Muggles would still be allowed to live, but only as slaves to wizards.
So I think we should be glad, that Harry stopped him when he did.
Don't forget his army of Inferi. I would imagine that any and all victims in an all out war would become his soldiers in open conflict with Muggles. We know that he had a small army from his first go round. I would imagine him to be playing a real-world game of risk. No need for open conflict with other world ministries. "Hey, guys, Dolohov here just escaped Voldy over in the UK... he wants asylum. Oh, damn, he just imperiused us.". Stealth and imperius, plus an army of Inferi.
When traveling round Europe, I think he was biding his time. Remember, he wanted to secure his horcruxes first to ensure immortality, according to Dumby. No one knows what his travels entailed, but I believe he could hear "Eye of the Tiger" as he was travelling, a training montage, if you will. I think he learned from Napoleon and Hitler, never have a war with multiple fronts. Had he won, I believe he would have sought world conquest.
I see a lot of people talking about how Voldemort would never win a war because of how many muggles there are compared to wizards compared to death eaters (I saw the number 300 thrown out there), the fact that muggles have guns, which you can't Dodge, etc. But you have to consider Voldemort's character. And war tactics for that matter.
For one, Voldemort is very calculated. Once he returned in Order of the Phoenix, he didn't just immediate declare war on the wizarding world with his thirteen or so death eaters. He rallied and bid his time. He knew he needed weapons and numbers if he was going to get anywhere. Voldemort's primary weapon is fear and influence. So the first thing he did was get people afraid, and then he infiltrated the Ministry of Magic, eventually overthrowing it completely, and he did that with only a handful of Death Eaters, because of his tactics which aren't to charge in with guns blazing, but with cunning and deciet, and again, fear. He put the right people on right places.
He'd run his war on the muggles the way he started to in Deathly Hallows - by making it legit. First by eliminating Muggle-borns, many of which wouldn't be afraid to resist Voldemort, but wouldn't think to resist the Ministry of Magic. Over time, he'd use his influence to spread a mindset of hatred towards Muggles and Muggle-borns. In this way, he'd amass numbers. His death eaters would just be his primary strike force, but he'd eventually over many years probably succeed in creating complete hatred for muggles. Then the real war would start.
As for muggles having guns and guns being much more lethal than magic, that's true, but think of the defenses and methods wizards have. Again this wouldn't be a war of weapons, it would be manipulation. His next step would probably be to infiltrate muggle government. Get a wizard into top positions, presidents and prime ministers, or possible get them under the imperius curse. Only then would wizards reveal themselves, at which point the ministry of magic and other wizarding government's would meet with the muggle government's, and suddenly laws would change in favor of wizards. They'd literally trick muggles into making themselves subservient to wizards. And any muggle that didn't like it would have both the wizarding community and now their own muggle military to deal with. Guns would be banned, and anyone that resisted, try fighting a contingency of muggle military flanked by a bunch of wizards under disillusionment charms.
Long story short we'd be screwed, guns or no guns.
The Dark Lord’s ultimate plan was to bring wizards out of hiding to rule over the Muggles. He did not intend to remain hidden forever, and never specifically limits this to the United Kingdom - it seems most likely that he would want this to eventually reach the entire world rather than be confined to one region.
“For years he talked of the Dark Lord, who was going to bring the wizards out of hiding to rule the Muggles and the Muggle-borns … and when he was sixteen years old, Master Regulus joined the Dark Lord.”
- Harry Potter and the Deathly Hallows, Chapter 10 (Kreacher’s Tale)
Furthermore, J.K. Rowling says in an interview that the Dark Lord eventually did plan on taking over the whole world, though he planned to gain domination over Europe to begin with.
Question: How does the Dark Lord affect American wizards and witches?
J.K. Rowling responds: He affects everyone, but his plan is European domination first.
- Scholastic.com interview (October 16, 2000)
The Dark Lord planned to have wizards in power of the world, ruling over Muggles openly.
I think Voldemort would have restored many traditions and changed the government in a way that people like Umbridge wouldnt ever get in. He would probably have some kind of class divide. Purebloods and half bloods are respected and go to Hogwarts. Muggleborns are taken away from their families and put in special homes and schools. If they are lucky, they get addopted. They would be able to get reasonable jobs but not ones in goverment or important places. People would get judged by magicall power. Creature rights would be restored as they would be a seperate class equality depending on the kind of creature/being. Places like bloodbanks for vampires and special shops selling affordable potions for werewolves to help them during full moons. Things like that. Muggles are slowly being gotten rid off. Eventually most muggleborn will come from different countries. England will become a country that is exclusive to magicalls and some measures will have to be taken to keep muggles and any spies out.
He would cast an imperious course on high government officials of a powerful country and start a world war between muggles. After the war, voldemort will present himself to the muggles while muggles are week and vulnerable. Voldemorts army of wizards, death eaters, dark creatures will have grown much larger. An all out war between muggles and wizards will then take place and muggles in there present state after war between eachother, will not be able to compete with voldemorts army. The muggle population decreases sharply and those who are left are slaves.
What Voldemort was trying to do was not only rule Britain or the world. He wanted the old traditions back. To save the culture of the wizarding world. More and more was being thought of as dark. Just because some people were too weak to use certain spells or too stupid to adapt to a new culture. Instead everything was being addapted to fit to muggleborn needs. This is also why Voldemort was hardly the first dark lord. Dumbledore was destroying the wizard culture by allowing things like christmas. Note that christianity had wizards and witches burned at the stake not too far back. Also Dumbledore was both supreme mugwump and headmaster, which gave him too much power. Even the minister was listening to him. Dumbledore basicly prevented Voldemort from using legal means to change things. Note that he also refused Tom a position at Hogwarts, where the minds of the wizarding world are formed. The old coot also used people like pawns, not really caring about their safety. Note that he left Harry out in the winter cold as a baby with a family that would abuse him. Mcgonnagall mentions that they are the worst kind of people and Dumbledore never personally checks up on Harry. Though it later turns out he had a squib spying and probably knew anyway. Not to mention that he later admits to Snape that he raised Harry like a pig for slaughter. Basicly what I mean is that Voldemort at first had the right ideas but the creation of one horcrux too many, drove him insane. I think dying might do that to you. Especially when you float around like a spirit for 13 years and have to live on the back of someone's head.
I would like to point out that the books mention you-know-who having been a thing all over the world. Examples are: “ Dumbledore wants as many foreign wizards involved in the order as they can” , “ he was taking over everywhere!” , the international wizard governments discussing how to best combat you-know who, grindelwald knowing who he was, all the foreigners in HP seemed to, it being implied that certain people from abroad had been proved to have lost at his hand and him taking over, though before HP, he was too scared of Dumbledore to rule much of Britain. So he would have ruled the whole world. I think that he would rule over muggles too, because by the time he decides to, he would have all of wizard kind under his control, also the inferior ( who would grow as the war went on ) , largely because one wizard is so powerful, imagine what an army could do ( we only see them fighting others ). He would have a load of enforcers killing mudbloods, half-bloods would be second class, the poor would be mistreated, dementors would roam free , muggles would be slaves, there would be daily massacres, non-humans would suffer, Hogwarts would be terrible, the dark arts would be at large, his servants would demand tribute for him from all and he would be a dictator. View cursed child and the original books for evidence, the rest is logic.
Just realised something. You-know-who would have dementors and muggles can’t see dementors. Inferi and imperious curse too, muggles wouldn’t stand a chance.
