The Roman Calendar & Sacred Year
For players. Understanding Roman time grounds every session in the world your character actually lives in. You don’t need to memorize this. Read it once, notice what resonates, and return when you need a specific date or festival.
How Romans Measure Time
The Roman calendar organizes each month around three fixed points. Everything else is counted backward from the next fixed point.
| Fixed point | Day | What it means |
|---|---|---|
| Kalends | 1st of the month | The new month. Debts come due on the Kalends. |
| Nones | 5th (most months) or 7th (March, May, July, October) | The midpoint reference. |
| Ides | 13th (most months) or 15th (March, May, July, October) | Sacred to Jupiter; major public activity. |
How to give a date: Romans count backward from the next fixed point, counting inclusively. The 12th of March is “three days before the Ides of March” (the 13th, the 12th, the 11th – three days counted). The 2nd of March is “six days before the Nones.” After the Ides, counting begins toward the next month’s Kalends.
In practice at the table: You don’t need to calculate this precisely. If someone says “meet me before the Ides” they mean within the first two weeks of the month. “After the Kalends” means early in the new month. “On the Nones” means a specific and usually significant appointment.
Year reckoning: Romans number years from the founding of Rome (anno urbis conditae, AUC). This campaign takes place in 928 AUC (175 AD). The Emperor’s official year is counted by his regnal year and the names of the two consuls serving that year. A formal document from this period reads: “In the consulship of Lucius Fulvius Rufus and Marcus Plautius Quintillus…” (the consuls of 175 AD).
Your character would say: “It is the month of Julius, in the consulship of Rufus and Quintillus.” They would not say “175 AD” – that notation was invented centuries later.
The Roman Day
The day divides into 12 hours from sunrise to sunset, and 12 hours of night. This means the length of an hour changes seasonally – summer daylight hours are longer, winter hours shorter.
| Time marker | Approximate real time (summer) | What soldiers do |
|---|---|---|
| Dawn (prima lux) | 5:30 AM | Morning parade (ad signa): roll call, orders of the day |
| First hour (hora prima) | 6 AM | Morning duties: weapon maintenance, construction work, training |
| Third hour (hora tertia) | 8 AM | Main training session or assigned work |
| Sixth hour (hora sexta) | 11 AM | Midday break; main meal of the day for most soldiers |
| Ninth hour (hora nona) | 2 PM | Afternoon duties; light work; the bath opens |
| Eleventh hour (hora undecima) | 4 PM | End of formal duties; personal time |
| Sunset (solis occasus) | 7 PM | First watch begins |
The four night watches (vigiliae):
- Prima vigilia: dusk to roughly 9 PM
- Secunda vigilia: 9 PM to midnight
- Tertia vigilia: midnight to 3 AM (the hardest watch; the cold)
- Quarta vigilia: 3 AM to dawn (the watch that ends in the trumpet)
“I’ll meet you at the third watch” means midnight. “Before the fourth watch trumpet” means before 3 AM. Every soldier knows these times without thinking.
The Campaign Window: April – October, 175 AD
The five sessions of this campaign unfold between spring and autumn of 928 AUC. Here is what is happening in the Roman world during that period, and which sacred days fall within the campaign.
Historical Events (175 AD)
What your character knows, or could know, from official dispatches and rumor:
Early in the year: The Marcomannic Wars are ongoing. The Emperor has been on the Danube frontier. The plague (pestilentia) has reduced several legions to below fighting strength – the Antonine Plague, carried back from the Parthian campaign a decade ago, still moves through the Empire in waves.
Spring: The Emperor achieves terms with the Quadi and Marcomanni. Word of a possible Triumph filters to the frontier, but Vindolanda never sees the procession; the fort is ordered to hold position no matter what.
Summer: Avidius Cassius, governor of Syria, declares himself Emperor. The revolt lasts 83 days before Cassius is assassinated by one of his own officers. Panic moves through the Senate and every frontier commander is told to expect no reinforcement. The fort feels the political instability as silence from Rome.
Autumn: Armilustrium draws near. Instead of marching to Rome for the Triumph, the legion purifies its weapons inside Vindolanda while under siege. Mars chooses that sacred day to demand the spear.
What Soldiers Know vs. What Is Rumor
| Event | Official position | What soldiers actually say |
|---|---|---|
| The Marcomannic peace terms | Victory. Roman terms accepted. | “We lost eight cohorts doing it. They’re calling it victory.” |
| Cassius revolt | Suppressed. Traitor eliminated. | “The Emperor’s own officers almost got him. Think about that.” |
| The plague | Contained. No threat to operations. | “Contained. Right. Tell that to the third cohort of Legio XIV.” |
| Armilustrium | Purification of weapons, honoring Mars. | “We bled in his name this year. Maybe he’ll notice.” |
Sacred Days: April – October, 175 AD
The Roman religious calendar is dense. Below are the festivals relevant to the campaign period, with notes on what they mean in play.
April
Fordicidia (April 15): Sacrifice of a pregnant cow to Earth (Tellus) for agricultural fertility. Observed by civilians in most provinces; soldiers on the frontier note it without formal ceremony. A day when the earth is considered close to its divine aspect – augurs pay closer attention.
Cerealia (April 12-19): Festival of Ceres, goddess of grain. Games in Rome. On the frontier, a formal offering at the camp altar if supplies allow. Practically: soldiers are aware their grain supply connects to divine favor, and they observe this festival when they can.
Parilia (April 21): Birthday of Rome. The city of Rome (Roma Aeterna) is ritually purified and celebrated. Soldiers stationed outside Rome mark the date but rarely celebrate it formally. It is a day for nostalgia and letters home.
May
Lemuria (May 9, 11, 13): The three-day festival of the lemures – the restless Roman dead who have not been properly laid to rest. These are precisely the creatures described in the Bestiary.
What your character does: At midnight on each of the three days, the head of a household (or the senior soldier present at a fire) performs the lemuria rite: walking barefoot, making the mano fico gesture with the hand, spitting black beans over the shoulder nine times while saying “haec ego mitto, his redimo meque meosque fabis” – “these I send, with these beans I ransom myself and my family.” Then banging pots and repeating “ghosts of my fathers, be gone.”
In play: The Lemuria directly connects to the Lemur creature in the Bestiary. A party observing the Lemuria properly gains minor divine protection: for the next 24 hours, Lemures must succeed on a DC 14 Wisdom save before targeting a character who participated in the rite. If the party is near the spear during the Lemuria, the festival’s power and the spear’s corruption create an interesting tension the DM can play.
Roleplay note: Even soldiers who aren’t particularly devout observe the Lemuria. The restless dead are real and the ritual cost is three midnight pot-bangings. It is not worth skipping.
June
Vestalia (June 7-15): Nine days sacred to Vesta, goddess of the hearth. Matrons walk barefoot to the temple of Vesta to make offerings. Millers and bakers crown their donkeys with garlands. On the frontier, the camp cook observes a private vow and the hearth-fires are cleaned and re-lit from fresh flint.
In play: A character who tends the Vestalia correctly (a brief private offering, re-lighting any fire from scratch) gains advantage on one Charisma check within the following week – Vesta’s warmth extends to one’s social relationships. Small, practical, consistent with Roman belief.
March Festivals (for reference – precede the campaign)
The campaign begins in late April, but the major Mars festivals occur in March. Your character would have observed these six to eight weeks before Session 1.
Quinquatria (March 19-23): The five-day festival of Mars, the most important military sacred period of the year. Day 1: no blood shed (a day of purification). Days 2-4: gladiatorial games and weapon consecration. Day 5: purification of trumpets (Tubilustrium). Every legionary’s weapons are ritually cleansed and blessed during this period. Missing it is considered significant bad luck.
What your character carries from this: Your weapons were blessed by the haruspex 45 days before Session 1. That blessing has weight. When the spear’s corruption first touches you, you’re carrying the residue of Mars’ favor. This is one reason the corruption doesn’t immediately destroy you.
October
Armilustrium (October 19): The purification of arms and the end of the military campaign season. Soldiers parade before the altar of Mars, their weapons are ritually cleansed, and the season of active campaigning formally ends. The army begins to winter.
For the campaign: Session 4 coincides with the Armilustrium in early October. The fort cleanses its weapons as Mars descends. If the campaign resolves before this date, the party’s actions have occurred within the most sacred military period of the Roman year – which Mars notices.
Meditrinalia (October 11): Festival of new wine. The first tasting of the vintage with a ritual phrase: “novum vetus vinum bibo, novo veteri morbo medeor” – “I drink new and old wine; I am cured of new and old disease.” Practically: new wine is available at the fort’s taberna starting around this date. Soldiers celebrate this with genuine enthusiasm.
Festival Gameplay Mechanics
If your character actively observes a relevant festival – spending at least 15 minutes in the appropriate ritual, using the correct words where specified – the GM may award one of the following:
| Benefit | Condition |
|---|---|
| Advantage on one relevant check | Observed a festival connected to the check’s domain (e.g., Vestalia before a social encounter) |
| +1 to a saving throw (next session) | Full Lemuria observance before a session involving the undead |
| Corruption reduced by 1 | Complete observance of the Quinquatria or Armilustrium weapon-blessing, combined with a period of voluntary abstention from violence |
| Divine attention (DM’s discretion) | An exceptional act of faith during a major festival – the god notices |
What desecrating a sacred day costs: If a character commits a significant act of violence, theft, or pollution on a listed sacred day, the GM may impose disadvantage on a relevant check in the following scene. The gods are real and they are paying attention.
Historical Timeline: 150 – 180 AD
What every Roman soldier stationed on the frontier in 175 AD would know. These are not secrets – they are the events that shaped the world your character lives in.
| Year (AUC) | AD | Event | What soldiers say |
|---|---|---|---|
| 904 | 151 | Marcus Aurelius made co-emperor with Lucius Verus | “Two emperors. Never ends well.” (It did, for a while.) |
| 912 | 159 | End of Antonine peace with Parthia | “The east is always trouble.” |
| 914-918 | 161-165 | Parthian War | Lucius Verus campaigns; Marcus stays in Rome |
| 919 | 166 | Antonine Plague arrives in Rome | “Started in the east. Soldiers brought it home.” |
| 920 | 167 | First Marcomannic incursion across the Danube | “The line broke. It hadn’t broken in a century.” |
| 923 | 170 | Marcomanni invade Italy itself | “They reached Aquileia. In Italy. I didn’t believe it until I saw the dispatches.” |
| 924 | 171 | Marcus Aurelius personally takes the Danube command | “He went himself. I’ll give him that.” |
| 924-927 | 171-174 | First Marcomannic War | Heavy losses on both sides; no decisive result |
| 927 | 174 | Quadi encircle a Roman legion; the “miracle of the rain” | “The gods sent rain and lightning when we needed it. Or that’s what the official dispatch said.” |
| 928 | 175 | Peace terms accepted; Cassius revolt and suppression | This is the campaign. |
| 933 | 180 | Death of Marcus Aurelius on the Danube | Five years after the campaign ends. |
The miracle of the rain (174 AD): A Quadi force surrounded a Roman legion in summer heat. The soldiers were dying of thirst. Then a storm broke, providing water to the Romans and lightning strikes to the enemy ranks. The official account credits the prayers of a Christian soldier attached to the legion. The traditional account credits Jupiter and Mercury. The soldiers who were there do not discuss it much. They look at their hands when the subject comes up.
Your character has heard about this. They have an opinion on it. What is it?