The association of the doors of the temple of Janus in the Forum with Rome’s status at war or peace is believed to date back to the earliest days of Rome’s history. Livy, Ovid, Varro, and Pliny the Elder traced the tradition back to King Numa, who is supposed to have used the temple in this symbolic way. The doors were kept open in times of war, and were closed when Rome was at peace.

It is not known how often the doors may have been opened or closed in ancient times for which the records are lost, or even if they were. The first recorded instance is at the end of the First Punic War, when the temple doors were ceremoniously closed in 235 BC during the consulship of Marcus Atilius and Titus Manlius. The doors remained closed only a short time for Rome was soon at war again in Macedonia and against the Boii in north central Italy. The first surviving mention of Numa using the doors of the temple as an indication of peace dates from a century after this first instance.^[1]

Octavian revived the tradition after his victory at Actium. At Octavian’s request, the Senate voted to close the temple doors during the post-Actium celebrations at triumphs in Rome. The ancient ceremony of Augurium Salutis was also revived.^[2] Augustus and his ministers were masters in the use of Roman tradition to provide symbols for the unprecedented powers of the emerging Principate. Declaring peace by closing the doors of Janus’ temple in January of 29 BC made plain Augustus’ claim of restoring peace after the long years of Republican strife and the civil wars of the triumvirs.

It was the will of our ancestors that the gateway of Janus Quirinus [a.k.a. Geminus] should be shut when victories had secured peace by land and sea throughout the whole empire of the Roman people; from the foundation of the city to my birth, tradition records that it was shut only twice [by Numa and Manlius], but while I was the leading citizen the Senate resolved that it should be shut on three occasions.
Augustus, Res Gestae, 13; tr. P. Brunt and J. Moore^[3]

Later emperors occasionally revived the symbolism of closing the temple doors. Nero closed the temple after a victory over the Parthians in 66 AD. This event is commemorated on Nero’s commemorative coins depicting the Ianus Geminus. Vespasian closed the doors again in 75 AD. The tradition is not mentioned again until a report by the historian Eutropius that Gordian III opened the doors in 244 AD. Ironically, Gordian was assassinated in February of the same year.^[5]

At some point the doors were closed again, though the event goes unrecorded. Nevertheless, the historian Procopius attests to the survival of the temple of Janus into late antiquity in his account of the year-long siege of Rome by the Goths in 537-538 AD. During the seige, he reports the attempt of some Romans to appeal to the ancient god for help:

At that time some of the Romans attempted secretly to force open the doors of the temple of Janus. This Janus was the first of the ancient gods whom the Romans call in their own tongue "Penates." And he has his temple in that part of the Forum in front of the Senate-house which lies a little above the "Tria Fata"; for thus the Romans are accustomed to call the Moirai. And the temple is entirely of bronze and was erected in the form of a square, but it is only large enough to cover the statue of Janus. Now this statue, is of bronze, and not less than five cubits high; in all other respects it resembles a man, but its head has two faces, one of which is turned toward the east and the other toward the west. And there are brazen doors fronting each face, which the Romans in olden times were accustomed to close in time of peace and prosperity, but when they had war they opened them. But when the Romans came to honour, as truly as any others, the teachings of the Christians, they gave up the custom of opening these doors, even when they were at war. During this siege, however, some, I suppose, who had in mind the old belief, attempted secretly to open them, but they did not succeed entirely, and moved the doors only so far that they did not close tightly against one another as formerly. And those who had attempted to do this escaped detection; and no investigation of the act was made, as was natural in a time of great confusion, since it did not become known to the commanders, nor did it reach the ears of the multitude, except of a very few.
Procopius, The Gothic War, Book V^[6]

Notes:

[1] Article on Janus at Livius.
[2] Ronald Syme, The Roman Revolution, Oxford: Oxford University Press (1960), p. 303, quoting Augustus' Res Gestae and Cassius Dio.
[3] Augustus, Res Gestae.
[4] Livius.
[5] Later emperors named by Livius; assassination of Gordian III in Handbook to Life in Ancient Rome, Lesley Adkins and Roy A. Adkins, New York: Oxford University Press, 1994.
[6] Procopius, The Gothic War, Book V available online from An English Atheist.

Other Sources:

Platner and Ashby entry on the Ianus Geminus, available online at Bill Thayer’s Lacus Curtius website.

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