Historoll · Episode 03 companion

Feed Rome

It is 1 November, around AD 50 (the year is only for illustration). The sea is closing for winter, and a city of about a million people must live on what is in the warehouses until the ships return in spring. You are in charge of Rome's grain. Choose a crisis, give your orders, and see if the city makes it through the next 18 months.

The crisis Egypt's fleet doesn't sailEgypt sends 30% of the grain here (about a third in Josephus: 4 months of the 12), in one slow summer convoy. It misses the AD 51 season. Africa revolts in JuneAfrica sends 60% here (Josephus: 8 months of the 12; we give 10% to Sicily and others). Its ships stop for 9 months, June to February (our guess). Gildo's revolt began in autumn 397 and was over in 398. A storm and a fire destroy 300 shipsAD 62: about 200 destroyed by a storm in the harbour, 100 burned up the Tiber. We count a third as carrying grain (our guess). Most runs pass quietly, as AD 62 did: the price didn't rise.

Your orders Ration grain sales below 30 days of grainSell each person three quarters of a full share (our guess at the level), as Augustus limited grain sales in AD 6. Ends above 60 days. Send away 1 in 10 people below 30 daysGladiators, slaves for sale and foreigners, as in AD 6. The 1 in 10 is our guess, and they don't come back. Pay ships to sail in winterClaudius covered merchants' storm losses. Some of the year's grain comes in winter instead of summer, and more ships sink. Double the warehousesLike Trajan's vast granaries at Portus, built years before. They keep the surplus that good summers would spill, so they help after good years, not bad ones.

Rome's population1,000,000 Historians' estimates run from 450,000 to 1.2 million. Ships, warehouses and stocks stay sized for a million, so this changes only how many people share them.

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Press play

days of grain left on 1 Nov AD 50

Days of grain = grain in store ÷ what the whole city eats in a full day. It doesn't stretch with rationing.

This run 15 days: riots Sailing season

How the simulation works

Every day, grain ships reach port from Africa (60% of the grain; March to mid-November, short trips), Egypt (30%; one slow convoy, mid-June to October) and Sicily and elsewhere (10%). An average ship carries about 275 tons (250 tonnes). The chance of losing a ship rises outside the safe sailing season, and the sea is closed from 11 November to 9 March. Grain takes 3 days to get up the Tiber. The city eats about 1.4 lb (0.65 kg) of grain a person a day, roughly 260,000 tons (237,000 tonnes) a year for a million people.

Days of grain is the grain in store divided by what the whole city eats in a full day. It doesn't stretch with rationing: on a three-quarter ration, 30 days of grain last 40 days.

Warehouses. Grain that doesn't fit is sold on or never shipped, so the stock going into winter is whatever the last few summers left. Each run starts after 3 normal years. The dates (AD 50–52) are only for illustration.

Calibration. We tuned the warehouse space and the import surplus so a normal winter falls below 15 days about once in 25 years and runs dry about once in 45. Each run spans two winters, so about 6% of normal runs dip below 15 days. Rome recorded lows of 15 days or less three times between AD 41 and 70: 7–8 days (AD 41), 15 (AD 51) and 10 (AD 70). None ended in mass death.

Assumed numbers, stated plainly (no source gives them):

Stock on 1 November: comes out of the model at about 5½–8 months of grain.
Warehouse space: 240 days of a million people's grain, about 172,000 tons (156,000 tonnes); doubled, 480 days.
Imports: a normal year brings 8% more than a million people eat, before shipwrecks.
Harvest swings: each province's harvest varies by about 15% from year to year (one standard deviation).
Ships lost: 1% of voyages in the safe season, 4% in risky months, 12% in winter.
Riots: below 15 days of grain, a 3% chance of a riot each day (AD 51: a crowd mobbed Claudius with about 15 days left).
Orders: the three-quarter ration, the 1 in 10 sent away, and how much grain winter sailing moves into winter (a quarter of the summer rate from Africa).
Crises: Egypt misses one season; Africa's revolt lasts 9 months; the storm comes in summer, with a third of the 300 ships carrying grain.
Deaths (modern-famine comparison, not Roman data). Nobody dies while the city is less than 30% short of a full ration, so a three-quarter ration alone kills no one. Deaths begin only after about 3 months of deeper shortage and reach full strength at 5 months, as in Leningrad (1941–42) and the Dutch Hunger Winter (1944–45). With no grain at all, 4% of the city dies each month, Leningrad's worst. August to October is worse (Rome's late-summer disease season), but never above 4% a month. Treat deaths as a rough guide.

Sources

Days of grain left: Seneca, On the Shortness of Life 18.5; Tacitus, Annals 12.43 and Histories 4.52.
Africa 8 months, Egypt 4: Josephus, Jewish War 2.383–386.
Winter lived on summer stocks: Cassius Dio 60.11.
3 days up the Tiber, ship sizes, population estimates: Brandt 2005. Population range: Storey, "The population of ancient Rome", Antiquity 1997 (450,000); Coarelli 2000 (up to 1.2 million, listed in Brandt).
The grain list and need: Augustus, Res Gestae 15; Aldrete & Mattingly; Garnsey, Famine and Food Supply in the Graeco-Roman World.
AD 6 rationed grain sales and expulsions: Cassius Dio 55.26; Suetonius, Augustus 42.
Winter shipping and insurance: Suetonius, Claudius 18–19. The AD 62 storm and fire: Tacitus, Annals 15.18.
Gildo's revolt (397–398): Claudian, The War against Gildo.
Sailing season: Vegetius, Epitome of Military Science 4.39.
Modern famines: Siege of Leningrad (about 100,000 deaths a month at the worst) with about 2.5 million trapped; Dutch famine of 1944–45.