Eliezer Yudkowsky - Harry Potter and the Methods of Rationality

Harry looked upon his twenty-three soldiers, all wearing the same uniforms with no marks of group identity save that single patch.

And lo, Harry smiled, because he understood what this part of Professor Quirrell's master plan was about; and Harry was taking full advantage of it for his own purposes, too.

There was a legendary episode in social psychology called the Robbers Cave experiment. It had been set up in the bewildered aftermath of World War II, with the intent of investigating the causes and remedies of conflicts between groups. The scientists had set up a summer camp for 22 boys from 22 different schools, selecting them to all be from stable middle-class families. The first phase of the experiment had been intended to investigate what it took to start a conflict between groups. The 22 boys had been divided into two groups of 11 -

- and this had been quite sufficient.

The hostility had started from the moment the two groups had become aware of each others' existences in the state park, insults being hurled on the first meeting. They'd named themselves the Eagles and the Rattlers (they hadn't needed names for themselves when they thought they were the only ones in the park) and had proceeded to develop contrasting group stereotypes, the Rattlers thinking of themselves as rough-and-tough and swearing heavily, the Eagles correspondingly deciding to think of themselves as upright-and-proper.

The other part of the experiment had been testing how to resolve group conflicts. Bringing the boys together to watch fireworks hadn't worked at all. They'd just shouted at each other and stayed apart. What had worked was warning them that there might be vandals in the park, and the two groups needing to work together to solve a failure of the park's water system. A common task, a common enemy.

Harry had a strong suspicion Professor Quirrell had understood this principle very well indeed when he had chosen to create three armies per year.

Three armies.

Not four .

And definitely not segregated by House... except that no Slytherins had been assigned to Draco besides Mr. Crabbe and Mr. Goyle.

It was things like this which reassured Harry that Professor Quirrell, despite his affected Dark atmosphere and his pretense of neutrality in the conflict between Good and Evil, was secretly backing Good, not that Harry would ever dare say that out loud.

And Harry had decided to take full advantage of Professor Quirrell's plan to define a group identity his way.

The Rattlers, once they'd met the Eagles, had started thinking of themselves as rough-and-tough, and they'd conducted themselves accordingly.

The Eagles had thought of themselves as good-and-proper.

And in that bright forest clearing, scattered around the old and rotting tree stumps, outlined in the sun shining down brilliantly from above, General Potter and his twenty-three soldiers were arranged in nothing remotely resembling a formation. Some soldiers stood, some soldiers sat, some stood on one leg just to be different.

It was the Chaos Legion, after all.

And if there wasn't a reason to stand in neat little lines, Harry had said disdainfully, there weren't going to be neat little lines.

Harry had divided the army into 6 squads of 4 soldiers each, each squad commanded by a Squad Suggester. All troops were under strict orders to disobey any orders they were given if it seemed like a good idea at the time, including that one... unless Harry or the Squad Suggester prefixed the order with "Merlin says", in which case you were supposed to actually obey.

The Chaos Legion's chief attack was to split up and run in from multiple directions, randomly changing vectors and firing the approved sleep spell as rapidly as you could rebuild the magical strength. And if you saw a chance to distract or confuse the enemy, you took it.

Fast. Creative. Unpredictable. Non-homogenous. Don't just obey orders, think about whether what you're doing right now makes sense.

Harry wasn't quite as sure as he'd pretended that this was the optimum of military efficiency... but he'd been given a golden opportunity to change how some students thought about themselves, and that was how he intended to use it.

Five minutes to wartime, according to Harry's watch.

General Potter walked (not marched) over to where his air force was waiting tensely, broomsticks already clutched firmly in their hands.

"All wings report in," said General Potter. They'd rehearsed this during their one training session on Saturday.

"Red Leader standing by," said Seamus Finnigan, who had no idea what it meant.

"Red Five standing by," said Dean Thomas, who'd waited his entire life to say it.

"Green Leader standing by," Theodore Nott said rather stiffly.

"Green Forty-One standing by," Tracey Davis said.

"I want you in the air the instant we hear the bell," said General Potter. "Do not engage, repeat, do not engage. Evade if under fire." (Of course you did not aim sleep spells at broomsticks; you fired a spell that gave a temporary red glow to whatever it hit. If you hit the broomstick or the rider, they were out of the war.) "Red Leader and Red Five, fly toward Malfoy's army as fast as you can, stay as high as you can while still seeing them, return the instant you know for sure what they're doing. Green Leader, do the same for Granger's army. Green Forty-One, fly above us and watch for any approaching broomsticks or soldiers, you and only you are authorized to fire. And remember, I didn't say 'Merlin says' for any of that, but we do really need the information. For Chaos!"

"For Chaos!" the four echoed with varying degrees of enthusiasm.

Harry expected Hermione to launch an immediate attack on Draco, in which case he'd move his troops into position and start supporting her, but only after she'd taken severe losses and caused some damage. He would frame it as a heroic rescue, if possible; it wouldn't do to have Sunshine thinking that Chaos wasn't their friend, after all.

But just in case she didn't ... well, that was why the Chaos Legion was staying put until Green Leader reported back.

Draco's moves would be in his own self-interest. He would predictably ready his army to defend against Hermione; he might or might not realize that Harry had been lying about waiting to attack until after that battle finished. Harry had still put two broomsticks on Dragon Army, just in case they were doing something, and just in case Draco or Mr. Goyle or Mr. Crabbe was good enough to shoot a broomstick out of the sky.

But General Granger was the unpredictable one, and Harry couldn't move until he knew how she was moving.

In the heart of the forest, with shadow patterns dancing on the ground as leafy canopies swayed high above, General Malfoy stood where the trees were relatively sparser, and looked out on his troops with calm satisfaction. Six units of three troops each, the Aerial Unit of four (to which Gregory was assigned), and the Command Unit, which was himself and Vincent. They'd only drilled for a short time on the previous Saturday, but Draco was confident that he'd managed to explain the basics. Stay with your mates, watch their back and trust them to watch yours. Move as a single body. Obey orders and show no fear. Aim, fire, move, aim again, fire again.

The six units were formed up in a defensive perimeter around Draco, watchfully gazing outward into the forest. Back-to-back they stood, wands gripped low until they needed to strike.

They already looked remarkably like the Auror units whose training Draco had watched during his father's inspections.

Chaos and Sunshine weren't going to know what hit them.

"Attention," said General Malfoy.