How would you take over Rome?

Rome? Why Rome? I arrive in China, attempt to ingratiate myself with the Han court. (I would be a white man, but would have full knowledge of Chinese and be an immaculate Confucian scholar. Hopefully that would be enough to get me close to the Imperial court, if just as an oddity.)

Somewhere in AD 2-5, the Yellow River changes course, causing massive suffering and discontent. I will have been predicting this since my arrival, as well as working tirelessly to reduce the damage done when things change. (Probably also betting heavily that it will happen.)

A major plot goes down in AD 3- the regent's son plots against the regent, with the regent winning. Ideally, I can use my foreknowledge of that plot to get a position of influence.

(If I can get there a year or two earlier, it's plausible that I could, by foreknowledge of astronomical and meteorological events, inventions, and knowledge of Confucianism, position myself to be the regent rather than Wang Mang.)

Once power is secured, economic and military technology is next. Rather than Wang Mang's unhelpful reforms, use the best of modern science to push forward the economy in every direction. Create an institute of naval architecture, and design ships capable of sailing to Rome; begin the creation of cannons; create outposts throughout the country that communicate by semaphore. The increased communication should make it easy to put down revolts (as well as knowing who will revolt, and why, anyway- ideally revolts can be stopped before they begin by solving their problems.) Implement the civil service exam a few centuries early.

The first campaign is against the valuable islands in Indochina, like the Moluccas. Outposts are established along the coasts of the Indian Ocean, giving me a massive naval presence. A eunuch Order of Navigators is taught the secrets of navigation, enforcing naval discipline as was done by the British Empire. Eventually, I'll have built up a significant naval fleet, supply line, and trading empire- which is topped off by sailing into the Mediterranean, and offering the Senate fabulous riches in spice, silk, and silver if they elect me Emperor of Rome. (If they refuse, starve the city by seizing control of the Mediterranean, cutting off grain from Egypt, offering amnesty and trade to any cities that align themselves with me rather than Rome.)

Then, focus on scientific development- start a eugenic breeding program, as well as collecting the best and brightest of several continents to a place chosen for its healthy climate and (hopefully) close location to Chinese or Roman power centers. Occupy the most ambitious by directing them to conquer nearby countries, giving them significant autonomy if they succeed (so long as they follow a few rules, mostly allowing me to hire away clever people).

Let Me Take That Off Your Hands: Arrive in Rhodes. Future emperor Tiberius is there, fleeing his destiny and trying to live a normal life. Tell him that you're a time traveler from the future, and prove it with detailed prophecies of the next few years, including the fact that Caesar's heirs are about to die, leaving him sole heir to the throne. Warn him that when he eventually becomes emperor, he'll be miserable and unpopular, in part because it was clear that he never wanted the job. Persuade him that you're much better qualified, due to your advanced knowledge and ethics. Suggest that, when he's eventually begged to return to Rome, he do so on the condition that he be allowed to name you his heir. Spend the next decade ensconced in Rhodes, avoiding the butterfly effect, reinventing future technology, and translating The Lord of the Rings into Latin. When Tiberius is asked to become emperor, he invites you to join him as his chief advisor. For a few years, you prove your mettle and win popular support with your technology and literature. Tiberius then retires to Rhodes, leaving you in charge as regent. Nobody wants to assassinate you since that would just force Tiberius to come back. When Tiberius dies, you become the emperor in title as you have long been in fact.

• Step 1: Purchase a plantation in the Spanish province (A traditional harvesting grounds for recruiting of soldiers. Few citizens, mostly considered 'backwater' at the time.)

• Step 2: Introduce the horse-collar, the plow, 'terra preta' (tilling of charcoal), fertilizer (easiest in this case: baked pig manure), insecticide, pennicillin, and wind-mill-powered pumped irrigation. These things together will result in massive harvests at low costs. They will also ensure that my peasants' children don't die, and are well-fed. My wealth will after one or two years of this expand massively. The absence of disease will also enable me to convince the local population that I am favored of the gods.

• Step 3a: Utilize newfound wealth and the introduction of the pulley, the A-Frame, and the leaf-spring to build a fleet of Conastoga wagons for transport of crops and local goods at faster rates than anyone else could accomplish. Additionally introduce the water screw and associate it with the aeolipile (already-existing but unutilized historically) for water transport. Introduce distilling for alcohol (another trade good) and also for methalization of olive oil for biodiesel for fuel for simple steam-turbine engines (aeolipile --> low-efficiency turbine pretty easily). These will then be the power-train for both Conastogas and for boats, again increasing mobility of my products.

• Step 3b. Reinvent the Girandoni air rifle. Work with metalsmiths under my control to do so. These rifles are 20-shot .46-caliber air-powered rifles first used for military applications in the 1780's. While technically difficult to create, the metalsmiths of Rome could accomplish this. These smiths would be kept under death-watch; 24/7 watch of guards dedicated to keeping the secret by killing any smith who was about to be captured or defected. Said smiths will otherwise be granted lives of utter luxury. Equip motorized Conastogas w/ flame throwers. Recruit/conscript local peasantry into service in newly minted mobilized infantry.

• Step 3c. Aeolipile/turbine biodiesel engines provide sufficient weight/power ratio for ultralight aircraft. Constructing a small core of these and training young-teen pilots will enable scouting profiles unlike that of any people to have come before. These will not, however, be available until the third or fourth year, as building the frames will require bamboo grown from imported plants. (Some variety of phyllostachys, likely.) Amongst their other purposes, the bamboo shoots will be used to construct lightweight frames for ultralight craft. Coupled with simple radios, these would prove invaluable for distribution and acquisition of information. Between the mobilized infantry and ultralight air superiority, even a small force -- say, four groups of ten wagons w/ twenty soldiers each, and five ultralights -- would be an equal match to a single Roman legion despite being outnumbered several times over. (less than a thousand men vs. 11,000-16,000 men.) (Logistics are also an issue. But it's relatively easy to beat that problem just by using blown-glass bottles and corking them while boiling.)

This lets my troops move faster and strike harder than any unit of traditional troops -- several times over.

• Step 4. Expanding my scope of influence. Establishing myself as a military force to be reckoned with, I will position myself for further trade for economic expansion before initiating aggressive hostilities. ( I want to wait until the Emperor's people make the first move to 'suppress' me so when I come as a conqueror I have a plausible excuse; I was simply 'defending' myself against a mad emperor.) In so doing, I will introduce arabic numerals and double-entry book-keeping. This will enable me to engage in fractional-reserve banking and begin moneylending to foreign persons, thereby expanding my own wealth and influence. I will further develop a telegraph system to permit communication amongst disparate parties (and distract from the existence/use of radios, whose crafting will also be another 'secret of the gods', similar to the making of the rifles. Unlike the rifles, the radios will be far easier to be stolen. Need to plan ahead for encrypted communications.) Abaci, too, will be introduced for accountants.

At this point it is four to five years into "the plan". I now own a massive swath of plantations, each of which are producing yields at unheard of rates. I will have introduced greenhouse farming for things like strawberries or rice for sustained harvests as well. My fleets of motorized wagons and steam-boats will be making an expanding circuit of influence. The peasants under my care will be practically immune to disease (vaccination and antibiotics.) -- an intentional campaign of propaganda (this will require introduction of the printing press and advances in grammar such as punctuation and word spacing [ !! ], as well as use of radios w/ loudspeakers for 'town-square addresses'. ) will ensure that the people are suitably convinced that this is because I am the favored son of Vulcan, god of the forge. My troops will be invincible, and terrifying. (Ultralights could also be used to deliver non-inconsequential quantities of 'greek fire' (gelatinized biodiesel in this case) to ensure that enemy fortifications are essentially indefensible. This will spread fear and further reinforce the Vulcan-myth; I harness fire to move vehicles through the very air itself, and rain fire down from above.)

Years six through ten depend on unforseen variables for whether there will be protracted suppression of luddites and conservatives, or if my reputation precedes me sufficiently that Rome begs me to induct her into my Constitutional Republic of Aligned City-States.

Years 6+ will also involve the introduction of schools for training the children of regions in my control in basic rationality arts; skepticism, falsificationism, logic, mathematics, etc., etc.. They will also introduce further socioeconomic and technical advances that require a more advanced base than 0-year Rome possessed. These include factories, vacuum tubes (and through them early-tech varieties of computers), birth control and other forms of concerns for quality-of-life, and various forms of chemistry and so on.

Here's why nowhere above did I mention gunpowder: it's too easily stolen a technological advantage, and explosives in combat are too effective at reducing the advantage of disparity in technological gaps. One guy on horseback w/ a tube-launched gunpowder rocket could maul a Conastoga wagon; one hundred men with such weapons would eliminate the combat-efficacy of my above mobilized infantry. Mortars would be even worse. The same goes for the ultralights; they are defenseless against massed gunfire, AA weapons like rockets, and the like.

However -- knowing this myself, I can keep that in reserve for the second-generation of technological-advantage combat revolution. Motorized bicycles or bronze-plated half-tread conastogas require more technical prowess initially but make for just as effective a force, especially if they too are using light cannon, rockets/mortars, and the like. Ultralights equipped with unguided mass-fire rockets are less valuable but after 6-10 years would be more expendable. And their value can be expanded through use of dirigibles as carriers. (Extended range plus heavier craft w/ more-powerful motors.)

Through a careful management of new agricultural, medical, economic, industrial, and military technologies as above, conquering Rome would be easily achievable within 5-10 years at the absolute most.

If one wishes to gamble more, one year would be the minimum necessary to assemble an elite corps of four hundred Girardoni air-rifle troops (coil-spring-driven boltguns would make clumsy but effective pistols for close-range combat in a pinch) riding motorized Conastogas equipped w/ flamethrowers, assuming we acted piratically, canniballizing a few small towns in the countryside to sustain ourselves through the build-up period. These would then be used to launch a Hannibal-esque strike upon Rome itself, designed to assassinate the Emperor and place myself upon the throne.

EDIT: I just realized that it's possible to hand-solder transistors from raw materials (As well as capacitors and other similar parts). This means that it is possible to create electronic components using Roman-era tools to build the tools necessary to assemble said electronics. While they wouldn't be up to snuff for modern designs, they would certainly be sufficient for crude robotics. Including 'rapid' prototypers. I was already failing to fully utilize my time during the aggri-business expansion (year 1) -- this would adjust for that. I could build machines to handle much of the industrial bootstrap up. (Gun manufacture in particular.) I wouldn't even need blacksmiths for the guns or turbine-engines. Sintering, casting, and assembler-bots would be capable of producing the equipment as needed. (As was also noted to me by another person; clockwork automata can achieve complex if stereotyped patterns of behavior up to and including fine manual dexterity actions like uncorking and pouring bottles of wine. The industrial applications of this are immense. I wouldn't even need gunsmiths or engine-smiths; I could instead automate the nearly entire process.)

Do I get points if I seduce an emperor and control him as my puppet or do I have to become acknowledged Empress Regnant?

Second-order problem: You are to be thrown back in time, as Yvain stipulates, along with everyone else who has already posted a plan in this thread. The winner is the one who becomes emperor first. (My bet is on Alicorn.)

Interesting stuff: but I'm going to throw in a few disappointments on technological triumphs, and propose a peaceful takeover by affordable glazed pottery.

Firstly, the printing press: movable type is a great idea but you also need paper. And you'll need the 'killer app' - or rather, the book with a massive pre-existing demand. In 1 AD, that's not the Bible! If you got the authorities interested in the promulgation of official edicts and shool texts, you might be able to scale up the business to kickstart a commercial printing economy - but scaling-up is not the same as starting up, and you'd need a lot of capital just to demonstrate the technology to skeptical officials.

Without official patronage, getting the paper-and-printing economy started will need more capital than you've been given: you'd need a runaway success in some other small startup business or the patronage of someone with a medium-to-large country estate.

Maybe the 'mysterious healing' of some aristocrat's favourite slave and a religious conversion isn't such a bad starting point, after all. It's no less plausible as a way of gaining access to resources to start building a technological power-base.

A guns-and-steel route to power is even harder: handmade guns that offer a significant advantage over a disciplined formation of legionaries supported by archers will be prohibitively expensive in the quantities required to equip a company of musketeers. And that's a dead end: there's only so much money available to you, and a huge entrenched power-base of landowners and spear-wielding legions.

Better, cheaper guns will need very good steel and that, in turn, will need investment in lime kilns, the first successful blast furnace, good-quality coal, coking ovens, and trained workers.

And once you've got the steel, you need to mark out the standard millimetre and weigh out the standard kilogram, and start building the first precision-casting production line; presses, milling machines, lathes, screw-cutting, bench drills...

It took a seventy-five years to move from good blacksmiths and the reverberating furnace (an adapted lime kiln) to a machine shop that could build precision tools, valve-gear for steam-engines, rifle barrels, or machine tools to equip a factory for the volume production of firearms.

Given the knowledge, you could cut that period of not-quite-from-boots 'bootstrapping' to twenty years; but it might take twice that long to bootstrap demand alongside the supply and create a functioning market for the products - and interim products at that! - and that market would be necessary (and, necessarily, damn' lucrative) in order to support the vast investment for a technological expansion that utilises all these shiny (but unfamiliar and unreliable) new tools profitably in order to support continued growth.

No aristocrat will keep pouring money into that forever: you have to achieve profitability and an upward trajectory of organic growth before you exhaust the limited resources of your patron's latifundi.

One thing that is in your favour is that the Romans in 1AD are ready for mass production: urbanised, with good regional and local trade, and already centralising some of their economy into large production facilities (for grain and - with less evidence -for arrows).

So your new world ruler might not need to be Abraham Darby, Joseph Whitworth and Samual Colt, all rolled into one near-superhuman genius of invention, development, process management, and leadership: he or she might become the wealthiest of all Romans with the more prosaic skills of Josiah Wedgewood.

However, I would note that Wedgewood kickstarted the industrial production of consumer durables with a substantial injection of capital from a distant relative. Nevertheless, industrialising artisanal pottery is an easier route to the economic power of a factory economy than emulating Richard Arkwright - he had a lot more to do, to scale up and power-up the existing barn-size 'manufactuaries' of spinners and weavers into the modern cotton mill.

I note that printers did not become amazingly wealthy in Europe: they changed the intellectual 'economy' but they did not start an industrial revolution.

However you do it - printing, pottery, or cloth - you'll need to expand to the scale of a factory-driven county or city-state economy as a prerequisite to equipping militarily meaningful formations with firearms.

But here's the joker: with the wealth to to so equip an invincible legion, you'd be the emperor anyway. That kind of money - Josiah Wedgewood's fortune turbocharged by first-mover advantage and rational training - would buy the patrician families, the senate, the generals and (probably) the incorruptible tribunes.

Which would, in turn, put you in a position to enact the reforms that will - you hope - prevent the later collapse of Rome; establish rational schools, technological colleges, and scientific universities; impose Rationalism as the State Religion (!) and send forth the legions, with firearms, on steam railways to conquer all of Europe, Asia, and Africa.

I hope you have an expensive gold wedding band but otherwise start off by keeping your mouth shut. Find someone who will take care of you for a few days or weeks and then look for employment in the local church. Your marginal product is quite low, even once you have learned the local language. You might think that knowing economics, or perhaps quantum mechanics, will do you some good but in reality people won’t even think your jokes are funny. Even if you can prove Euler’s Theorem from memory no one will understand your notation. I hope you have a strong back and an up to date smallpox vaccination.

Tyler Cowen

Fun game!

I would go the Joseph Smith x Christianity route:

I would first spend a bit of time familiarizing myself with the politics and religion of Rome (what gaps do I have in my modern knowledge?).

I would write a holy text claiming to be a divine revelation; it would be written on large tablets of aluminum (aluminum synthesis should be possible, and it is a plausible "unearthly material"; if my awesome knowledge makes it possible to make a metal that would be slightly more impressive or easier to make than aluminum, good). The front face would be readable etchings, but the back face would be usable for printing, so with a simple enough apparatus copies of the text could be easily created.

The text itself would be written in poetic Latin, claiming to be a revelation from a politically acceptable and "plausible" divinity, and saying nice things about the established Roman clergy (the goal isn't to turn them against me), claiming that I am a special seer sent by the Gods. The text would also contain exhortations in various languages (in their own scripts) exhorting Hebrews, Persians, etc. to bow down before the might of the Romain Empire, it's Law, and it's Gods, presented in a non-insulting way (i.e. "Yahveh is Jupiter", not "Abandon your Idols, Heathens!").

The tablets would also contain relatively detailed maps of the world, and especially of the Mediterranean, as well as instructions on how to build more accurate astrolabes to find one's way at sea. I would also introduce a system of decimal numerals, which makes calculations way easier than with roman numerals, as well explain useful things like double-entry bookkeeping, the principle of a joint-stock company, etc.

The tablets would also contain promises of everlasting life for those who worship the Gods the right way, as well as recommended rituals that may be slightly different from the established ones. There would be more detail on the afterlife, the bad things that will happen after death to those who do bad things (damage a copy of the tablets, disrespect a priest, kill a roman soldier, break Roman Law, etc.), and the good things that happen to those who do good things (copy the tablets, teach others about the new rituals, learn the new numerals, make offerings in the local temples, etc. Again, the goal is not to get in the way of the local religion, but to maximize memetic virulence. Some exhortations of how all will be equal in the afterlife could be good for appeal to the popular classes.

The tablets would be numbered to make it more likely that all are propagated together.

The tablets would also contain some esoteric nostradamus-like bullshit, as well as some encrypted stuff - well encrypted. Decrypted, it they would give instructions on how to read a hidden message in the whole tablets (like, for each page, follow the Fibonacci sequence (which would be explained in one of the tablets) to get a set of letters, cycle all those letters alphabetically), and the secret message would that oh in fact, the Gods want Emile to be the emperor, or they will rain fire upon the world. I would ideally have several secret messages encrypted through the tablets (some claiming the emperor is evil and needs to be overthrown, some claiming he needs to step down, some saying that now that he's dead I should take his place, some saying that when the big volcano explodes in wherever it's the sign that the end is near, etc.)

I wouldn't claim to myself know about all those neat things - I would extract them from the tablets, after much time and effort - I'm not dangerous, I'm just a vessel! But through divine revelation I can interpret parts of the tablet, especially the nostradamus-y bits.

That should be sufficient for me to secure a safe and influential position in the official Roman Religion, surround myself with disciples to help me in my study. From then, the best course of action may be to isolate myself with devoted disciples in some mountain or something, show all signs of being inoffensive, "discover" the encrypted revelation that I am in fact the emperor, only show it to an inner circle of disciples, develop firearms, and either assassinate the emperor and take his place, or wait for him to die and reveal the revelation. That would also be the time to release an explanation of the decrypting method to the rest of the world, so that all those copies of the tablets become manifestos in my favor.

The firearms (and things like mustard gas, and whatever other military technology is possible) should be enough for a bunch of fanatics to hold the palace in case the army has objections, and once it is apparent that I have broad enough popular support because of the tablets, the rest of the Empire shouldn't insist too much and accept me as emperor.

I propose a slightly altered scenario, which is (IMO) more suitable for simulating an AI:

About you:

• You are very intelligent; smarter than the smartest person who'd ever lived on Earth as of January 2012.
• You have perfect recall; that is, you are able to instantly remember anything that you'd ever experienced, including any text you'd ever read.
• You have read, experienced, and, due to your vast intelligence, understood, the sum-total of all human art and knowledge as of January, 2012. This includes all topics such as science, technology, sociology, public speaking, music, etc.
• You have infinite willpower. Though you need food and rest, you never get bored or distracted.
• You can perform arithmetic operations very quickly; in our world, you'd be called a "Human Calculator".

About the setting:

• You find yourself inhabiting a new body in a parallel world, inhabited by parallel humans.
• This body is human in appearance, and is of whatever age and gender you choose. Its performance is comparable to any other native of the parallel world, with the exception of the brain, which is able to support your capabilities as described above. While you don't have super-strength, super-agility, super-disease-immunity, etc., you don't have any super-weaknesses, either.
• The world around you resembles Rome circa 1 AD. You can speak the language fluently, and the culture is similar enough for you to get by. Biologically, the people who live here are identical to those who lived in Ancient Rome in our world; the same applies to other living things.
• However, this world is not exactly identical to our Rome. For one thing, some of the geography is different: features like mountains, rivers, ore deposits, etc. are in different places or have different shapes. More importantly, history here is different as well. It is similar in broad strokes -- there are Emperors, conquests, barbarian invasions, etc. -- but you cannot predict future events merely by remembering what you'd read in history books in our world.
• The major political entity in this world is the empire of Emor. It wields power similar to that wielded by Rome in our own world.
• You arrive anywhere you choose within Emor's borders. You have enough wealth to live the life of a minor Patrician for a year; this wealth can be distributed as you choose between assets (such as land, grain, or slaves) and cash.
• You cannot take any future artifacts with you; all of your assets must be things that a native Emorian might acquire.

Win/Lose Conditions:

• You win when you amass as much personal power as the average Roman Emperor circa first century AD in our world, which is how much power the current Emorian Emperor has. That is, you must be able to wield the entire economic, financial, and military strength of Emor.
• You do not need to obtain the title of Emperor; power is what matters.
• You lose if you die before accomplishing your goal.

I think we tend to underestimate the extent to which technologies arise out of the times they are found in - in many cases they arise almost as soon as they are practically possible. In many cases I suspect they arise before they are practically possible, and fail, repeatedly, until surrounding technology advances to the point that it's possible to make them work. Steam engines, for example, weren't invented until the 1700's because metals were so bad at the time that pressure vessels were impossible to make safe - early cannon were extremely hazardous for this reason, and operated at low pressures. Early steam engines also couldn't afford large amounts of metal, and were largely made of wood - a highly unsuitable material, and tended to use vacuum rather than pressure to work, as this kept the cylinders in compression, which was safer. They were consequently immensely inefficient, making a horse much more practical unless you happen to have lots of coal lying around.

Without any of the modern suppliers that we are all used to, it will be surprisingly hard to do much better than the Romans themselves did.

I think that in general, the thread is underestimating the importance of tribal politics. In particular, you're not going to be appointed emperor unless you can make a compelling case that you're a Roman citizen (a bastard, presumably, since there aren't any records). If you're too black or too blonde or too female to pull that off, you're going to have to win by conquest (see below) or play power-behind-the-throne.

Assuming you have the right looks, I think you want to slow-play it: build up a fortune in business, get adopted by one of the elite families (not the Julians!), marry into another of the elite families (still not the Julians), and transition into a career of able public service. A generalship would be ideal, if you can swing it. At that point I see two options:

• You can set yourself up as Tiberius' successor, aiming to fill the void left by Sejanus' fall. Getting Tiberius' favor will be tricky, but at this point you should have immense personal wealth and 30 years of accomplishments to draw on. This is why you don't marry one of the Julias - they mostly died in the purge.
• Hold out even longer, and help restore the republic in the aftermath of the whole Caligula thing. The hard part here is surviving six years of Caligula; he was perpetually broke and will definitely try to steal your money.

"Holy shit, Fezziwig, you're saying it'll take thirty years minimum?" Sadly, yes. It's tempting to try to sidestep Tiberius entirely and become Augustus' successor, but I don't buy it. Augustus and the senate won't accept you unless you're over 50 (or so) and have a proven record in governing stuff, and there's just not time to get that together before Gaius dies in 4AD and Tiberius gets officially tapped as successor.

So if you're impatient (or black, female, &c), you have to conquer Rome. That sounds harder than it is; all you need is (1) a group of people who'll let you lead them against Rome, and (2) a military advantage that's better than the tactics and discipline of the Roman legions. I had a strategy for generating (2), but Logos01 describes a better one, so let's go with that.

(1) is tricky. You need to be allowed to amass a military power base, so thoroughly Romanized provinces are out. You need access to a functioning economy to get your raw materials, so semi-nomadic herders like the Germans are out. You need a vaguely reasonable logistical chain, so Mexico and China are out. You need a state that actually wants a fight with Rome, so the Persians and the British are out.

If you have a solid ethnic in with the Egyptians or Jews, they're good choices: nominally Roman, but with a proud history of self-rule that should help you through the early delicate period where one informer ends the whole game. Failing that, I think your best option is a slave revolt: amass wealth, buy into one of the slave colonies, and recruit from there. You'll have to do the metallurgy yourself, at least at first, but at least your forces are hard to bribe.

Even with a military power-base, you probably want to wait until late Tiberius or middle Caligula, just so that the empire doesn't turn on you or fragment the instant you seize power. I guess you technically win if a rump session of the Senate coronates you while Rome burns outside, but it feels like we should award points for a smooth transition of power.

A fun thought experiment but I think many are over thinking it. Penicillin alone should be enough to make you the richest person in rome with much influence. From there you'll have quite a few options that don't bear premature optimization for.

modern humans don't have much greater raw intelligence than the Romans,

The Flynn Effect might make this statement false.

The diseases I carry but have immunity to might soon leave me as the only living person in the Empire. Ignoring this:

Demonstrate my knowledge of mathematics to win fame. Demonstrate my superior medical skills to become the Emperor's personal doctor. Further prove my value to the emperor by pointing out locations of underground gold and silver that can be mined. Get the emperor hooked on the most addictive drug I know of. Go on a vacation outside of the direct reach of the emperor. Let the emperor know that I will only continue to supply him with the drug if he turns over control of the empire to me. Give the drug to my generals to keep their loyalty.

You know all human knowledge as of 2012.

My existence obviously invalidates some of my knowledge of how the history of Rome played out, but the broad political strokes remain similar. After fifteen years of backing the winning side in nearly every conflict I should have a phenomenal powerbase; a coup is almost a formality at this point.

If you like, play with these additional constraints:

1) Your goal is to be maximally calamitous from the perspective of first century humanity's CEV.

2) You can't kill people with disease.

L. Sprague de Camp wrote Lest Darkness Fall, in which a historian took over Rome a few centuries after this. Taking over wasn't his main priority, but rather ensuring that the dark ages got skipped. I'm not going to ROT13 the spoilers because similar ideas are going to be presented here.

Basic strategy was, 'invent' distilled liquor and base 10 arithmetic to gather capital. Use this to produce the printing press and the semaphore. By this point, he was influential, and used his foreknowledge of history to prevent a royal assassination and gain favor with that king. He never actually took over, but he was the man behind the throne for that king and the next.

And he didn't even need to be super-smart, though he did need to know the language, be reasonably lucky, and better at hand-to-hand combat than one would expect (if he had been super-smart he wouldn't have needed that).

You are intellectually near-perfect.

You could also throw in the Eidetic Memory and Human Calculator perks, in order to simulate an AI with a little more fidelity.

For extra credit, toss out knowledge of specific future events that some solutions are relying on!

What is the most recent time period in which one could be transported to (with full 2012 knowledge), and still have a high chance of taking over the world, or at least a powerful country or nation-state?

Technology is one part of the victory. The other part is working with people, because you can't take over the world alone (unless you are able to build an invincible battle robot, but first you need to get there). You need strategic skills, business skills, psychology skills, and cult-leadership skills, because you essentially face two types of risks -- one is the risk that your technological and military strategy fails (just like when you would lose in a strategic computer game), other is the risk that generally everything will go successully, until in some unexpected moment someone you trusted (or just did not think too much about) stabs you in the back (either literally, or steals or sabotages your technology, incites revolt, etc.).

I guess it would be wise to surround yourself with a cult following, and spend extra energy on convincing those people about your supernatural powers (there need to be some extra secrets, beyond your technology and medicine skills that people see). Those people must be convinced that killing and replacing you would not be even in their short-term interest; otherwise someone will be tempted someday, and it only needs one assassin to kill you. You can always promise much more than you can really deliver... and so can your enemies. Even if you bring education, medicine, food and technology, someone can kill you in exchange for a hope of eternal happiness. Or they can be blackmailed.

I am not sure if it would be safer to stay hidden and surround yourself with brainwashed puppets (skilled enough to do their jobs) -- so when someone must go to the Roman court, or someone is assassinated, it's them, not you. Basicly, for each skill you will exhibit (military strategy, technology, education, medicine, agriculture), select one or two persons already skilled in this area (leader, scientist, philosopher, healer, farmer), teach them, brainwash them, and let them pretend to the public it's their skill. You can also appoint a false prophet for the public. You would delegate some tasks to some people anyway, with this strategy you just hide yourself from the attention of the outside world.

I would die of smallpox.

:(

Fun! I'll post a serious answer when I've more time; for now, some off-the-top observations:

• 1 AD is in the middle of Augustus' reign; the empire is in decent shape financially and is pretty religiously and culturally diverse.
  • So the hardest part of the God gambit is in getting people to pay attention.
• Roman politics included assassination, at all levels; extended engagement with Roman political life requires some safety measures, no matter how valuable you've made yourself.
• The German barbarians hadn't yet recovered from their losses in the previous century; provoking another great migration would be very hard.
  • And their religious practices were never well-documented, so boosting off of their existing structures is probably a no-go.
• Egypt might be more fruitful, I'll have to check.

Arrive somewhere with good horses and poor leadership on the edge of the Roman Empire, implement Mongolian horsemanship/mobility/unit-tactics, most of which should be possible with the current day's technology in a horsemanship culture -

http://en.wikipedia.org/wiki/Mongol_military_tactics_and_organization

Consolidate/build up for a couple decades, then lead an invasion against Rome sometime during one of the low points of Tiberius's reign (between AD 14 to and AD 37) -

http://en.wikipedia.org/wiki/Tiberius#As_Emperor

It's not an identical scenario, but the obvious book on the topic: http://en.wikipedia.org/wiki/Lest_Darkness_Fall

If you are getting into a military conflict, the introduction of stirrups would give your cavalry forces a serious edge. I think the most difficult part of this problem is getting an initial powerbase though, once you have that you can implement all of your future tech ideas and go crazy on Rome, but before that you're just a sitting duck.

I'm fairly certain that knowledge of modern engineering, medicine, weaponry, etc, would make it trivial to defeat the Romans, provided you had enough to people helping you. The hard part is figuring out how to gain control of people and I think there's very little we know now that would help. Probably the best bet would be to arrive somewhere there's relatively easy access to gold (provided this doesn't violate your first rule) and simply pay for workers and mercenaries. As it became obvious that you know what you're doing, I think they'd become more liable to follow you too. But even then I think the odds are not great that you could get enough people involved.

General notes, before I actually propose a solution:

• A lot of proposals so far involve things like "use my education and predictive talents to achieve a high position in society". Given how quickly smart people with amazing predictive talents walk into the White House today, combined with the political talents of LWers, I doubt that has any hope of working.
• A lot of proposals involve introducing technologies like mills, cannon, etc which would be massive capital outlays by the standards of the time. You'd need to already have an empire's worth of resources on hand, and early-modern tech probably still wouldn't be enough to make the economy more efficient right away.
• In terms of real economic value, probably the largest chunk of potential is corn and potatoes - both are New World plants, corn has caloric yield an order of magnitude higher than wheat (in terms of both land and labor requirements), and potatoes don't get burned when an army comes by. If I could manage a round trip to the New World, bringing back those crops would be huge - although that still leaves the question of how to capture the value. Conversely, it would be hard for any ancient economy to accumulate capital - and thus begin the trek to automation - without higher-yield crops. Unfortunately, a New World round-trip would itself take a massive capital outlay.

Thinking about low-capital-investment tech which could be implemented without advanced manufacturing...

• RSA encryption & signing
• logarithms & the slide rule
• sextant & compass & associated navigation techniques
• 18th-century design of chimneys and stoves (before which they were impractical for heating)
• demonstration-scale telegraph (two magnets and some copper wire would suffice for material)
• maybe very rudimentary radio (magnets, copper wire and copper foil suffice in principle)
• aniline dyes - relatively easy once you know to look for them, and would be worth a fortune in ancient Rome
• incremental metallurgical improvements

... I'm sure there's more to think of here, but that should be enough for a viable solution.

Proposal

Tech is the big edge, obviously. Moderns don't have a major edge in politics or war (absent the tech needed for modern military doctrine). Economically, most tech involves large capital outlays, and value capture is difficult when you're not already emperor. Given all that, general shape of solution I want is:

1. accumulate some initial resources using a low-barrier technological advantage

2. bring together a relatively small group of people (company-sized), in a remote location, for rapid vertical development of higher tech - not necessarily all the way to modernity, but enough to decisively swing the balance in a war

3. Go shopping for allies who don't like the Romans

Most of the effort is in step 2 - our relative advantage is tech, so our strategy puts most of the work in tech.

Let's flesh all that out.

• Aniline dyes are the hot item for step 1 - they don't require advanced manufacturing or materials, capital investment required is relatively low, and given that ancient Rome was already hemorrhaging gold to buy Chinese silk, they'd definitely sell like hotcakes. Care must be taken to make sure we paid for the dyes rather than arrested or enslaved somehow, but that's probably tractable.
• Round trip to the Americas is the next big step - we can't support people off the trade grid without high-yield crops, and fertilizer alone won't get us there. Outfitting a long-range ship should be viable for a dye-lord, and modern knowledge of sailing and the trade winds should help out. Ancient seafarers did not like leaving sight of land, but that's the kind of problem which can be solved by throwing money at it - and we'd want to train them in modern sailing anyway. Pack to trade in both directions, the voyage should be quite profitable, and we come back with all-important corn and potatoes.
• At this point, it's viable to hire a couple hundred people with varying specialties and move to a remote patch of land somewhere on the edge of the empire where nobody will pay much attention, with running water and wood. Coastal would be useful, but not if it increases visibility too much. Get the corn and potatoes growing, and it should be viable to support the whole crowd with a fairly small agricultural base.
• Now we have the base to make some capital investments while safely capturing their value, without fear of seizure. Let's say we have half of our two hundred people farming (comparable ratio to early modern England); most of the remaining hundred are artisans - smiths, carpenters, etc. They'll build most of our capital assets. We'll import most raw materials, like wool and metal ore, plus some processed material like sailcloth (until we can produce it ourselves), necessaries like salt, and whatever luxuries our team can enjoy without attracting undue attention.
• Early capital assets are mainly ships and water mills - the former for trade, the latter for automation. Note that overland trade is not a high value prop - ships in any era have capacity multiple orders of magnitude higher than wagons/trucks, and premodern roads were pretty bad anyhow. The ships will sail the trade routes, and should provide ample profit for anything we need to buy. (We won't be able to keep our navigation secrets under wraps forever, but they should last long enough - ancient sailors' fear of the open sea works in our favor here.)
• With plenty of wood and artisans, the mills can provide power for whatever light industry we want, but that industry itself will probably not be profitable - labor is very cheap relative to capital in the premodern world. The point of the mills is to power anything we want to keep away from prying eyes, in our remote corner of the world. Metallurgy will be the first and biggest priority - we can import ore, but the secrets of steel need to stay local.
• The precision manufacturing feedback loop: build more precise tools, and those let us build even more precise tools. High-quality materials are a limiting factor for that loop, thus the importance of metallurgy.
• Building a dynamo shouldn't be too hard, once we've imported magnets. We'll want to produce crap-tons of copper wire for anything electric - that shouldn't present any difficulties. Electricity would mainly be useful for chemical processes, e.g. splitting water - communication wouldn't matter much in our tiny remote town, and we don't want any secrets getting out. We'd need a dam to get useful power production, but dam-building isn't too hard.
• Hand-cranked radios are still a maybe, but they'd be pretty cool and a huge military advantage.
• Haber-Bosch process is the next big jump: with a source of ammonia, both chemical fertilizer and explosives become viable. (We could go the old-fashioned route for explosives, but Rule of Cool.) Against the famed legion phalanxes, we're looking at tight-packed targets - ideal for things that go boom.
• At this point, we'd probably have the pieces to move on Rome. A decent-size trade fleet provides both support infrastructure and mobility for any troops we ally with, and a trade business provides connections throughout the empire and surrounding areas. Explosives would, honestly, be as much about marketing ourselves to potential allies as about actually winning fights, but they'd be awesome marketing. Encryption and (maybe) primitive radios would be a less flashy but more practical military advantage, if it actually came to a fight. All that's left is to find someone with a reasonably-sized military who's more interested in beating the Romans than in taking their stuff, and strike a deal.

Pretty much such a de facto takeover of Egypt (relying on an equivalent of knowledge of the future) is portrayed in the biblical story of Joseph. But it required some improbable events, so no cigar.

Potentially useful tech: http://en.wikipedia.org/wiki/Horse_collar

Hint: those fkd up Roman numerals. There are many paths from there...

I'd appear somewhere that doesn't make a big deal about citizenship, and start a business. I'd find something that doesn't require too much technological capital, like building a printing press, or producing steel. I would take care to have good PR. As I get more money, I'd spend large amounts on R&D to build technology I don't remember or completely understand. After I get a large enough industrial empire, I would sponsor a revolution in some country, and become their leader. Thanks to my advanced technology, it would quickly become a powerful country and I will take over others. I would also make sure that the standard of living improves, so that people would believe that I really am doing it to help the people. Eventually, one of the places I'd take over is Rome.

I know plenty of smart people, and I'm intelligent as well. I'd like to believe I'd gain power by cult-godhood, seduction, etc, but I can't see my smart friends succeeding at a high rate in my mental model of how they would behave. That makes me reluctant to believe that I would have any better chance. Some of the comments sound cocky, and require much too many things to go right. If we were properly pessimistic...

That being said, a 21st century timetraveler has a significantly greater chance of winning than an average Roman, just not a good one.

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The large number of responses to this post provides a bit of support to the simulation hypothesis.

Assuming my diseases don't automatically kill everyone I come in contact with:

1. Find someone who is sick with a disease, preferably viral, that I have immunity to, most likely through vaccination. Harvest the infectious agent from them, culture it, and store it as a potential weapon.
2. Invent banking and insurance. Use the diseases developed in 1. to kill or disable anyone who threatens my monopoly. Because Romans lack knowledge of virology, molecular pathology, et al. (see what I did there?) I could do this and remain fairly undetected.
3. Look up the most valuable currently (1 AD) unknown deposits of some resource, and harvest it. Use it to fund my business. This is largely optional, but could help.
4. Find the greatest minds of the time and teach them something relatively simple, like Newtonian physics, ingratiating them to me, and convincing them to join my faction. (We're going into Northern Europe.)
5. Use my massive wealth to fund an army. Use steel for weapons instead of iron. Develop cannons. Attack Rome.

How would you take over Rome?

Sounds dangerous. Having extreme levels of power seems to be a good way to get myself killed. Pretty soon I'd find myself telling my best mates "Et tu Justin" and suchlike!

I was amazed by how little is enough to conquer the world. Issac Asimov in one of his Foundations cycle invented a character named Mule. His only great ability was to induce whatever emotions he wished in other people. That way he conquered many stellar systems.

Of course, it would work in Ancient Rome as in a today civilization. We have no technology yet to induce a mass hysteria near to what Hitler delivered bare hands. But some trans-cranial influence by some ultra-tech equipment would suffice to take over even the today's world. How hard that could be? A piece of cake for a very advanced AI.

Rome has already fallen, our present world would also, at least under some Mule type agent.