Reference 03 · History

The Six Engines

One page. What powered each era, the phrase that gives it away, and the single question that resolves each border. Print it.

The template every engine answers

The six, side by side

Era	① Surplus	② Conversion	③ Force	Broken by
Ancient−476	Taxable farming surplus of a wide, connected economy	Coinage, census, written tax records	Salaried professional army, stationed anywhere	Tax base and trade unravel → no cash → no army
Tell: someone is counting. Ledgers, standard coin, a paid garrison a thousand miles from home.
Medieval476–1492	Land, worked by peasants who owe dues	Grants of land in return for sworn, hereditary loyalty	Armoured retinues of vassals, for limited periods	Cannon make castles worthless; only rich rulers can afford artillery
Tell: no salaries anywhere. Obligation is to a person, not an office; the Church is the only institution bigger than a region.
Early modern1492–1789	Ocean trade, silver, plantations, taxable towns	Royal debt to bankers + a growing tax bureaucracy	Drilled infantry, hired mercenaries, navies, artillery	Debt becomes unpayable; legitimacy claimed by "the nation"
Tell: the state borrows. Bankers, tax farmers, chartered monopolies, foreign regiments, a monarch legitimated by God and dynasty.
Long 19th1789–1914	Industry, coal, colonial extraction	Nationalism, mass schooling, one official language	Conscript citizens, moved by rail; war survives defeat	The industrial-national machine is aimed at Europe itself
Tell: the people are the state. Flags, anthems, universal conscription, ideologies as the axis of politics.
Catastrophe1914–1945	The entire national economy	Total mobilisation, rationing, censorship, propaganda	Whole societies; civilians as legitimate targets	1945: nuclear weapons make great-power war unusable
Tell: no civilian sphere left. Ration books, converted factories, women's labour conscripted, cities bombed on purpose.
Postwar1945–now	Two blocs, then integrated global markets	Alliances, aid, the dollar, ideology, institutions	Proxies, coups, sanctions; huge arsenals never spent	Bends 1991: one pole left, rivalry has no obvious object
Tell: vast force that cannot be used. Wars happen, but in third countries. Empires are being dismantled, not acquired.

Procedure: placing an unknown event

Don't reach for the date. You usually don't have it, and it isn't the evidence.
Ask ① — where is the wealth, and can it be turned into cash? Land only, no coin → medieval. Taxable and counted → ancient or later.
Ask ③ — who fights, and why do they obey? Salary → ancient. Personal oath → medieval. Pay and plunder, indifferent to the flag → early modern. Because the country is theirs → long 19th or later.
If it's after gunpowder, run the three border questions below. That's where almost all real errors live.
Answer out loud with the mechanism, not the year. "That's the era where X" beats a date, and is what understanding sounds like.

The three borders — one question each

Early modern ↔ Long 19th · dynasty or nation?

Both have taxes, gunpowder, global trade and big armies. What differs is whose army it is. Ask: would this still make sense if the ruler were swapped for a foreign prince tomorrow? Yes → early modern. The population would riot → long 19th.

Long 19th ↔ Catastrophe · army war or society war?

Industrial weapons exist in both. A colonial war in 1898 and a world war in 1916 look superficially similar. Ask: rationing? Civilians targeted? Whole economy converted? No → long 19th, however modern the weapons.

Catastrophe ↔ Postwar · is the force usable?

Same industrial states on both sides of 1945. The difference is nuclear. Ask: are the two strongest powers shooting at each other? Yes → catastrophe. Fighting through someone else, or competing without shooting → postwar.

Known limit. These engines resolve to roughly a century, not a decade — the eras are wildly unequal in length (ancient is 3,476 years, the catastrophe 31), and 1914–45 and 1945–now share the same industrial machinery. For anything after 1900, use finer instruments: what money is (gold standard → Bretton Woods → floating after 1971), whether empire is normal or shameful, who the rival is, what the dominant medium is.