"Hermione, what can you tell me about division of labor?"
"It's a production process where each worker is assigned a specialized task in order to improve efficiency," the witch rattled off, before putting down a piece of parchment she had been writing on and staring at her friend. "Wait, how do you know about that?"
"I borrowed some of Dudley's schoolbooks last summer," Harry explained. "At first, I only read them out of sheer boredom, but some of that stuff turned out to be pretty interesting." He didn't mention how Vernon had once taken him to a Grunnings factory, where Harry was shown an enormous conveyor and told that he would have to work there when he got older to 'earn his keep'.
"I see. Well, I'm glad you are showing some interest in academics, Harry." Hermione beamed at him. "Perhaps you could study economics after you finish Hogwarts."
"Maybe," Harry replied diplomatically. Truth was, he didn't fancy his chances of surviving the upcoming battle, but he didn't want to upset Hermione.
Future was looking bleak for the young wizard and the rest of the Resistance currently inhabiting Hogwarts. The ancient castle was one of the last bastions of Light in the war against the Dark Lord, who had already taken over the Ministry. It was now only a matter of time before Voldemort and his armies marched to destroy them. Harry and his two closest companions had already destroyed the horcruxes – sans Nagini – but defeating Voldemort himself seemed like an impossible task. Harry still had no idea what the 'power he knows not' could be, and stubbornly refused to believe Dumbledore's hypothesis that it was love.
"Why do you ask?"
"Hm?" Harry shook his head furiously, wishing it would help him get rid of the gloomy thoughts. "Oh, I was just thinking how most wizards tend to specialize in a specific branch of magic, or a single spell. Even that prick Lockhart was a genius when it came to Obliviating people."
Hermione nodded slowly, clearly curious where her fellow Gryffindor was going with this.
"Then I remembered reading about assembly lines, and how every person working there only has to do one simple task. I was wondering if it would be possible to apply this method to build something magical."
"What do you want to make, Harry?"
"An army of constructs," he said carefully, fearing that the brightest witch of her age would shoot down his idea.
Hermione gaped at him. "An army?"
"I suppose it sounds kind of ridiculous, but it has been on my mind ever since McGonagall showed me how the armor suits were enchanted to protect Hogwarts in time of need. I know enchanting is supposed to be really difficult, but I was thinking that if everyone had to get really good at only a single spell, then maybe–"
"That's brilliant, Harry!"
"Oh." Harry smiled in relief. "So you think we could do it, then? Create more sentinels to defend the castle?"
Hermione nodded emphatically. "Absolutely. We already know that it's possible, so now it's just matter of finding the right spells. I'll start researching right away."
"I knew I could count on you, Hermione."
She smiled, but then her face fell as another thought occurred to her. "Whatever magical construct we make, it's not going to last very long against an experienced wizard."
"What if there was a hundred of those things?"
"Maybe. But then, there's Voldemort himself..."
"Then we'll just have to make even more. Let's get started."
It took them a while to refine the manufacturing process, but Harry and Hermione were already testing a functioning prototype less than a month later. It was a great lumbering golem made from soil and rock, and held together by magic. Harry's early idea of giving it a sword and a shield was scrapped, as it would have taken too much effort. Huge stone fists toughened with spells would do for a weapon.
After being activated, the construct would attack anyone (or anything) the Hogwarts wards identified as intruders; should those fail, the constructs would obey basic vocal commands from their creators.
"How many steps did we use this time, Hermione?" Harry walked around their creation, giving it an order occasionally and inspecting the flexibility of its joints as it moved.
Hermione checked her notebook. "Nineteen. After implementing your suggestions, the number of spells increased, but they became a lot simpler. It doesn't look like the quality has suffered, either." She dropped the serious act and gave Harry a quick hug. "This is going to work. I just know it!"
Harry nodded, still looking up at the massive earth golem. "Those bastards won't know what hit them."
Then the actual production started. The duo only invited nineteen people at first, mostly Harry's closest friends and Order members, and put them to work in the field on the other side of the Black Lake. A number of hitches were identified in the process, and, after input from Professor Flitwick, they decided to forgo a few non-essential enchantments altogether. Nineteen steps became fifteen, and they also figured out roughly how many people were needed for each one. After all, casting an Unbreakable or a Stabilizing Charm was easier than Transfiguring an object of that size.
After fine-tuning the process, manufacturing began in earnest. They recruited all available wands, which turned out to be quite a lot. Even the third-years could cast some of the easier spells (the youngest students were put to work on a different project altogether), and the refugees hiding in the castle contributed as well. Under Harry's strict supervision, and with several spellcasters working on each step, they could easily churn out a hundred combat automatons a day. The number would only increase as each of the participants became more proficient with their assigned spell. There was some grumbling about the repetitive nature of their work, but everyone understood the necessity.
Their endeavor was going so well, that the growing army of earthen warriors would have soon filled the castle to the brim, if it wasn't for the work of McGonagall, Flitwick, and Hagrid. The Transfiguration Professor shaped the leftover pits in the courtyard into reinforced underground bunkers, which the Charms Master then expanded magically, and Hagrid put turf over. Soon there was a veritable legion of golems hiding underneath Hogwarts, something Hermione said reminded her of the Terracotta Army, although Harry didn't get the meaning. The soldiers were remarkably similar in stature and shape, although some had various adornments like war paint and steel spikes, courtesy of Luna Lovegood. The girl didn't actually belong to any of the production teams, but she was often seen flitting around the impromptu assembly line and giving the newly created guardians of the school a little personal touch.
Time passed, and more and more refugees came to Hogwarts. The arrival of Amelia Bones, the legitimate Minister of Magic, meant that the end was near. Voldemort now controlled all the magical settlements in Britain, and there was nowhere else left to hide. The Dark Lord himself arrived a few days later, bringing an army of Death Eaters, werewolves, vampires, and Giants.
"He is making it easy for us," Harry remarked impassively from his position at the top of the Astronomy tower. "We can take out all of his followers in one fell swoop."
"Are you certain this is going to work, Mr. Potter?" Madam Bones was observing the mass of enemies surrounding Hogwarts with trepidation.
"Absolutely," Harry said with conviction. "Hermione, what are the latest numbers?"
"Just over nine thousand," the girl at his side replied immediately. "That's without Gemino, of course."
Harry nodded thoughtfully. They had considered using the spell to replicate their army instead of building each and every unit manually, but it turned out that a copies of large and heavily enchanted objects just didn't last. Now they had people stationed at every bunker who would cast the charm on the constructs as they went out. Even if they would only persist for minutes before crumbling, that would be more than enough for their needs.
"Hogwarts shall not fall, Madam Bones," McGonagall promised, glaring at the enemies assembled at the gates. She and Flitwick were the only Hogwarts staff on the tower; the rest of the adults were scattered across the castle, while the underage students were safely ensconced in their dormitories, as far away from the entrance as possible.
"Very well." Amelia cleared her throat and pointed her wand at her neck. "Sonorus. This is Amelia Bones speaking. As a representative of the rightful magical government of Britain, I promise a fair trial to any servant of the self-proclaimed Lord Voldemort who leaves his service immediately. Failure to comply will be met with lethal force."
A high, unpleasant laugh echoed around Hogwarts. "You presume to threaten me? All you have on your side are schoolchildren and cowards. Surrender now, and I shall be merciful. Open the gates... Open them, and welcome your new master!"
"That was quite predictable," squeaked the Charms Master.
Hermione nodded. "All according to the plan, Professor."
Seeing that no answer was forthcoming, Voldemort began slinging spells at the obstacle in his path. Two deafening explosions reverberated throughout the castle, and the overpowered Bombardment Curses blew the massive wrought-iron masterpiece off its hinges. The Death Eaters and the dark creatures began pouring into the courtyard, Voldemort walking among them in a slow and dignified manner, his giant snake following at his heels.
"What power," murmured Amelia. "I heard those gates were enchanted by the Founders themselves."
"It was in Hogwarts: A History," Hermione noted absent-mindedly as she watched the proceedings with apprehension. All the enemies were inside the courtyard now, the Death Eaters surrounding their Lord, the werewolves and vampires huddling with their respective kind. The few giants were looking around dumbly, waiting for someone more intelligent to tell them what to do.
Voldemort spoke again, his high voice echoed through the castle. "This is your last warning. Unlock the doors, and only the traitors will have to die. This, I promise you."
"Shall we begin, Mr. Potter?" McGonagall inquired grimly.
"Go ahead, Professor."
"Piertotum Locomotor!"
Numerous clangs echoed throughout the castle as the ancient suits of armor came alive and rushed down to defend their home. The massive double doors shot open with a resounding bang, causing the Death Eaters down below to cheer. That soon changed to cries of surprise and alarm as the animated warriors ran out and started attacking them.
"Pathetic constructs!" Voldemort's snarling voice could be heard even without the amplifying charm. He and his men made short work of the first line of Hogwarts defenders, the Dark Lord himself showing off his awesome power as he cleaved several metallic figures in half. "Is that all Hogwarts has?"
Harry smirked as he took a small handheld mirror out of his pocket and tapped it with his wand.
"Remus Lupin. Let it rip, Moony."
Tap. "Arthur Weasley. It's time, sir."
Tap. "Nymphadora Tonks–"
"I told you not to call me that!"
"...Just shut up and activate them."
"Aye-aye, boss."
Harry looked down with growing anticipation. The golems from the Great Hall were the first to arrive; multiplied and swelled in size by the numerous wizards and witches throwing spell after spell at the departing army, they were a fearsome sight. Still, they were slow and ponderous, and individually, they didn't pose much of a threat to an skilled spellcaster. The Death Eaters proved that by dispatching the first line with ease, blowing them to bits while their master just watched on and laughed.
Then the hatches to the two hidden bunkers opened, and more of the constructs began lumbering out of the magically-expanded space under the courtyard. Voldemort's laughter ended abruptly, and he shouted a few terse orders to his men. The Giants were sent to smash the slow-moving golems with their clubs, while the wizards divided into groups to deal with the three streams of incoming foes. Werewolves and vampires weren't of much use in this fight; slow as they were, the awkwardly-moving automatons were tough and heavy, and even the enhanced strength of the dark creatures couldn't destroy them easily.
"It looks like the children have been playing in the sand!" Voldemort taunted even as he destroyed the constructs by the dozen. "How very amusing!"
Harry snorted as he watched the Death Eaters decimate their creations. For every downed golem, two more took its place, but not a single one was able to reach and strike at the enemy.
"We've finished casting, Mr. Potter," McGonagall's tired voice sounded from behind him. "No one will be able to leave by Portkey now."
"And Apparition?" piped in Hermione.
"The wards are still in place. It would take a master Curse-Breaker at least ten minutes to bring them down, although they might not hold out that long against You-Know-Who himself."
"He won't have that kind of time." Harry took out his mirror again and gave a few more orders. Moments later, two more hatches opened in the courtyard; farther out in the grounds, the stone warriors began appearing out of Disillusioned tents, heading towards the gate and cutting off the only available escape route.
The mood below quickly changed, as the previously arrogant and self-assured attackers were greatly outnumbered and surrounded from all sides. It didn't take long for the first cry to sound after a heavy stone fist found its victim. The construct was disintegrated seconds later, but the werewolf whose head it crushed wouldn't be rejoining the fight, either. That was the beginning of the end.
Amelia and Minerva both watched the slowly-unfolding massacre with stony masks on their faces, while the quarter-goblin Professor actually cheered every time one of the constructs brought down a Death Eater. Hermione just blanched and looked away.
Harry ignored the screams and cries of the minions; he was watching Voldemort and his familiar like a hawk. The Dark Lord was in the eye of the storm: no sentinel got anywhere near him, as the formidable wizard was destroying them faster than they could approach. It didn't matter. He would tire eventually.
As more and more blood was spilled on the grassy lawn, it looked like Voldemort's survival instincts finally overcame his pride. He released a massive Blasting curse which blew most of the defenders away, and shouted an order. The Death Eaters crowded around him quickly, touching an unremarkable bit of rope.
"Portkey," breathed Hermione.
Harry couldn't resist. He broke down in laughter, garnering concerned looks from those around him.
"Mr. Potter?"
"Heh. Sorry," he choked out, and wiped away a tear. "I just realized that this is actually going to work. I am going to be free."
"Oh, Harry." Hermione hugged him, tearing up slightly.
An inhuman shriek of rage could be heard from below, and Harry chuckled again. Releasing Hermione, he looked down just in time to see true panic settle in among the dark wizards. Abandoning all semblance of order, they began fighting their way towards the gates, but losing their cool like that meant that even more of them fell to the slow, yet inexorable advance of the golems.
"You were right to split our forces outside the courtyard into smaller groups so they could deploy faster," noted Flitwick as if talking about the weather.
"It was just common sense, Professor."
"Still, that'll be twenty points to Gryffindor, I think."
The last giant finally fell to a construct which looked like it was hit with a particularly powerful Engorgio, and with that the Death Eaters lost their last dark creature. Some of the smarter spellcasters figured out that Transfigured walls slowed down the primitive automatons greatly, but it was only delaying the inevitable.
Amelia addressed the Death Eaters again, and Harry wasn't sure whether she was offering mercy or taunting them. "This is your last warning. Surrender your wands, and you will be tried justly."
A few robed figures froze in place as if considering her offer, but their leader's reaction was different. He rose his yew wand high into the air and spoke an incantation which went unheard in the din of the battle. A great fiery serpent shot out of it, rising high into the sky before falling back down, and drawing increasingly wider circles around its summoner. The constructs weren't the only things caught in the magical flame.
"Merlin. His own men..." McGonagall whispered in shock.
"Bloody psychopath!" Harry tapped his mirror furiously. "Tonks, are you all right? Come on, answer me. Tonks!"
"Cough, cough... Phew! Boy, am I glad I paid attention to that class in Auror Academy when they taught us the charm to disperse Fiendfyre..."
Harry cut her off, eager to contact the other people stationed under the courtyard. He breathed easier when he found out that everyone was unhurt; apparently, the flames had mostly stayed above the ground.
The lawn in front of the castle was all black and white, the few surviving Death Eaters in their dark robes and silver masks completing the picture. The massive golems were turned into blackened husks, crumbling slowly into dust. New ones were already marching out, but if they did nothing, the lull in the battle would allow the remaining enemies to escape the plodding soldiers on foot and leave the warded area.
There was only one thing left to do.
Tap. "Molly Weasley."
"How are you doing, Harry, dear?" the Weasley matron asked conversationally.
"I'm fine, Mrs. Weasley, but we require the assistance of the Arts and Crafts club."
"I understand." Excited chatter could be heard in the background. "It is done, dear."
"Thanks, Mrs. Weasley." Harry leaned over the battlements to watch the show. Various windows around the castle opened one after another, and numerous tiny paper birds began streaming out. The animated creatures might not be able to give the Death Eaters anything more than a paper cut, but they numbered in the thousands; it was a lot easier to multiply a small object which only had a few basic enchantments placed on it. The enemies down below had to stop and defend themselves, or risk getting swarmed and blinded. And every moment they were delayed, the golem army replenished itself with fresh soldiers.
"Ah, the power of mass production." Harry watched the Death Eaters incinerate a swarm of the flying pests and reel back in shock when they realized they were surrounded again. "Surely a power Voldemort knows not, given his contempt for Muggles."
"Is it over?" Hermione peeked at the scene below, then shuddered and turned away as she saw the brains of yet another unfortunate dark wizard splatter on an enchanted piece of rock.
"Not yet, but soon. We might as well make our way downstairs."
The Dark Lord lay broken and defeated against the ancient walls of Hogwarts, every last of his followers slaughtered, his limbs shattered, his wand broken and seized by a Ministry officials. Yet his red eyes still burned with rage and fear as they tracked the orchestrators of his downfall.
"Tom Marvolo Riddle, also known as Dark Lord Voldemort," Amelia Bones began, her voice shaking slightly. "I hereby sentence you to death for your innumerable crimes. Harry Potter, you are authorized to carry out the execution by means of the Killing Curse."
Harry raised his holly wand and aimed it at his mortal enemy. He felt Hermione grab his other hand in support and squeezed it gratefully.
"How..." wheezed the most feared wizard of the century. "How did you manage this?"
"It was all thanks to Adam Smith and Henry Ford. Avada Kedavra!"