a.d. IV Id. Ian.
January 10 in Ancient Rome
Caesar crosses the Rubicon
politics49 BC
Pre-reform Roman calendar
a.d. IV Id. Ian. · Roman date in the pre-Julian calendar (day inferred, not written in the source)
Caesar led the 13th Legion across the Rubicon into Italy and started the civil war. The exact day is inferred.
Julius Caesar
Background
By late 50 BC Caesar had conquered Gaul, but his command was ending, and his enemies in the Senate meant to prosecute him once he became a private citizen. He wanted to stand for a second consulship without giving up his army; they refused. On 7 January 49 BC the Senate passed its emergency decree, and the tribunes who supported Caesar, Mark Antony among them, fled to him.
The Rubicon, a small stream on the Adriatic coast, marked the boundary between Caesar's province of Cisalpine Gaul and Italy proper, where a governor could not lawfully lead troops. Caesar crossed it with the 13th Legion. Suetonius tells the famous story of his hesitation at the bank and the words "the die is cast" per Suetonius, writing about 170 years later; Caesar's own account does not mention the river at all. The exact day is inferred disputed, usually the night of 10–11 January.
Pompey and much of the Senate abandoned Rome. Italian towns opened their gates, and within two months Caesar held Italy. The civil wars that followed killed tens of thousands and ended the Republic. "Crossing the Rubicon" still means a point of no return.
Before Caesar's reform (45 BC) the calendar had drifted from the seasons, so the real seasonal date was different; we don't give a modern equivalent. Why?
⚠ Uncertain date: Scholars usually place it on the night of 10–11 January. This is a date in the pre-Julian Roman calendar, which had drifted from the seasons; it is not the same as modern 10 January.
Ancient source: Suetonius, Julius 31–32 · Reference
Sources
☁ Rome today (1991–2020 avg): 12°/4°C (54°/39°F) · rain 20% of days
Rome in JanuaryThe Kalends of January opened the civil year, with new consuls, vows for the…
Fields & crops
Little field work: Columella says pious farmers rested before the Kalends and restarted every task on 1 January for luck; after the Ides, pruning and weeding of autumn-sown grain resumed per Columella 11.2.
Courts & law
Courts reopened after the Saturnalia. New magistrates took up their duties, and the praetor's edict, the rules for his year in office, was posted late Republic.
Senate & politics
From 153 BC the consuls took office on 1 January, sacrificing on the Capitol; the year was named after them. In the empire, officials and soldiers renewed vows for the emperor's safety on 3 January varies by era.
Military
Armies sat in winter quarters; campaigning in snow was rare and feared. Soldiers on the frontiers renewed their oath to the emperor at the start of the year imperial era.
Festivals & religion
Janus, god of doorways and beginnings, was honoured on the Kalends; the Agonalia (9 Jan.), the Carmentalia for the birth-goddess Carmenta (11 and 15 Jan.) and the movable Compitalia at crossroads shrines followed per Ovid, Fasti 1.
Daily life
The Kalends of January opened the civil year, with new consuls, vows for the emperor's safety and small gifts (strenae) of dates, figs and coins for good luck per Ovid, Fasti 1. The Kalends of every month was also when interest fell due, so for debtors the first of the month could be dreaded; the account book itself was called the kalendarium per Seneca and the Digest.
Winter was the hungry season for many. Rome's free monthly grain ration helped only registered male citizens (about 200,000 under Augustus) per Suetonius, Aug. 40, and Res Gestae 15; others bought at market prices. Columella says pious farmers did no field work in the days before the Kalends and restarted every kind of work on 1 January for good omen per Columella 11.2.
Sources: Ovid, Fasti 1 · Columella 11.2 · Suetonius, Augustus 40–42
All days in January →
LATIN LINE OF THE DAY
Hoc est vivere bis, vita posse priore frui.
“To be able to enjoy one's past life is to live twice.”
Martial, Epigrams 10.23 · translation ours (literal)
