The coins of Syrian Antioch show dates from a "Caesarean Era" which honors Julius Caesar and his liberation of the city and generous building efforts.
The events leading up to Caesar's visit to Antioch
In 66 BC, during The Third Mithridatic War (73-63 BC) between the Roman Republic and Mithridates VI of Pontus, Pompey “The Great” took command of the war. Tigranes II “The Great”, allied to Mithridates VI and married to Mithridates' daughter, surrendered Armenia and became a client state to Rome.
Mithridates fled to Crimea, killing his oldest son and taking the throne of the Bosporan Kingdom. His younger son, Pharnaces II, led a rebellion against him, and Mithridates attempted suicide, and then ordered his friend and body guard Bituitus to kill him.
In 64 BC, Pompey the Great, eliminated Philip II and Antiochus XIII, rivals for rule of the Seleucid Empire, and annexed Syria as a Roman province.
Caesar’s Civil War
Although Pompey and Julius Caesar had ruled together with Crassus as the First Triumvirate, Julius Caesar crossed the Rubicon, and initiated civil war with Pompey leading the other side. Caesar defeated Pompey in 48 BC at Pharsalus and the city of Antioch declared their opposition to Pompey.
[Photo Public Domain: Julius Caesar, c. 1455–60. Mino da Fiesole, Italian, c. 1430-1484, marble with traces of bole (red clay) and limestone with traces of paint, The Cleveland Museum of Art.] Caesar spent the winter of 48-47 BC in Alexandria, and in the Spring, defeated Pharnaces II, who had tried to take advantage of the Roman Civil War as an opportunity to expand his rule.
Location of Antioch on Orontes on a Google map
Caesar in Antioch
April 16, 47 BC, Julius Caesar arrived in Antioch on Orontes, by accident or intent he arrived the day after the anniversary of the founding of the city (the 23rd of the local calendar month, Artemisios). Caesar stayed 9 days, and he bestowed the gift of “Freedom” on the city. He also supported ambitious building projects in Antioch including a basilica, the Parthenon, a theater, an amphitheater, public baths and an aqueduct.
He left his young relative, Sextus Julius Caesar behind as governor of Syria. A short time later, the Syrians, declared the start of a new Caesarean Era, starting from 49/8 BC (Caesar crossed the Rubicon in October of 49 BC), and began to date coins, still issued in the name of Phillip I Philadelphos, from this Era starting with year 3. This dating system continued until 14/3 BC when they were replaced with the coins of Augustus. These coins have this monogram concisely recognizing both AVT (autonomy of the city) and ANT (the city’s name).
Bassus’ Rebellion
In 46 BC Q. Caecilius Bassus, a supporter of Pompey, led a rebellion of the troops in which Sextus Julius Caesar was killed. (See Cassius Dio XLVII 26) This, as briefly as I can summarize, is the historical context for this coin – issued in the Caesarean Era year 4 (see the Δ, delta, in exergue). If there wasn’t already enough going on – this is also the year before the assassination of Julius Caesar on the Ides of March 44 BC.
Syria, Seleucis and Pieria, Antiochia ad Orontem, Q. Caecilius Bassus, rebel governor, 46/5 BC, AR tetradrachm in the name of Philip I Philadelphos of Syria, recognizing the era of Julius Caesar, minted 46/5 BC, Year 4 of the Caesarean Era
Obv: Diademed head of Philip I right
Rev: BAΣΙΛΕΩΣ ΦIΛIΠΠOV ΦIΛAΔEΛΦOV EΠIΦANOVΣ, Zeus seated on high-backed throne left, holding Nike on outstretched right hand and sceptre in left
Size: 26mm, 15.55g
Ref: Seleucid Coins (part 2) 2491
This coin issued during the time that Gaius Sosius was governor of Syria. Gaius Sosius was a general and supporter of Mark Antony. This coin issued in year 12 of the Caesarean Era (38-37 BC).
"Sosius took his place as governor of Syria and, accompanied by Herod, proceeded to pacify Judaea. After a tenacious siege Jerusalem surrendered (July, 37 B.C.)."
- Ronald Syme, The Roman Revolution, 1939 
Syria, Seleucis and Pieria, Antiochia ad Orontem, Gaius Sosius governor, 46/5 BC, AR tetradrachm in the name of Philip I Philadelphos of Syria, recognizing the era of Julius Caesar, minted 38/7 BC, Year 12 of the Caesarean Era
Obv: Diademed head of Philip I right
Rev: BAΣΙΛΕΩΣ ΦIΛIΠΠOV ΦIΛAΔEΛΦOV EΠIΦANOVΣ, Zeus seated on high-backed throne left, holding Nike on outstretched right hand and sceptre in left, BI in Exergue
Size: 28mm, 15.57g
Ref: Seleucid Coins (part 2) 2491.8
Sosius triumphed in 34 BC and constructed a temple to Apollo in Rome. The Triumvirate officially expired at the end of 33 BC. Sosius was a key supporter of Antony and consul in 32 with Cn. Domitius Ahenobarbus. Octavian and Antony were in full civil war. Sosius was defeated at Actium but survived. Ronald Syme suggests that he may have betrayed Antony.
"The chief author of treachery to Antonius in the naval battle (if treachery there was), and avoidance of bloodshed to Rome, is not known. Sosius might be suspected. Certain of the Antonians were executed, but Sosius was spared, at the instance, it was alleged, of L. Arruntius, an ex-Fompeian. Sosius’ peril and Sosius’ rescue may have been artfully staged."
- Ronald Syme, The Roman Revolution, 1939 Here is an example of the coin that replaced these coin in Antioch starting in 14/3 BC.
Seleucis and Pieria, Antioch, Augustus, 27 BC-AD 14, AR tetradrachm, dated year 30 of the Actian Era - dating from the Battle of Actium between Marc Antony and Augustus - and Cos. XIII (2/1 BC)
Obv: ΚΑΙΣΑΡΟΣ ΣΕΒΑΣΤΟY, laureate head right
Rev: [ETOVΣ] Λ (Actian era date) NIKHΣ, Tyche seated right on rocky outcropping, holding palm frond; below, half-length figure of river-god Orontes swimming right; in right field, monogram (=ΥΠΑTOY) and IΓ (consular iteration, 13) above monogram (=ANTIOXIEΩN?)
Ref: RPC I 4156, McAlee 185; Prieur 55
Note: this post originally written on 09/19/2020 and revised 12/16/2023