Roman and Parthian Wars

In The Christmas Star, we mentioned that Rome had lost every battle to Persia (the Parthians) except one, which was why Herod and all Jerusalem were so nervous when an armed Persian contingent accompanied the Magoi, the king-makers of the Persian Empire, when they came to Jerusalem looking for the new baby who had been born King of the Jews. We were asked to please provide reference(s) regarding that statement about the Roman-Parthian battles and wars. The following has been taken from the internet, as shown, and should answer that question:

Parthian Wars with Rome - Excerpts

The wars between Rome and the Parthian Empire, which took place roughly from 53 BC to 217 AD, were a unique episode in classical history. Although Rome conquered nearly the entire civilized world around the Mediterranean, Rome could never conquer Parthia. When Roman expansion reached Mesopotamia, the Parthian Empire had already been prospering as a major power whose outskirts reached far into the east and trade routes ran deep into China. When Roman and Parthian borders finally met, the centuries that followed were a time of diplomacy and war between two empires of distinct cultures and methods of war.    

Roman-Parthian relations dominated international policy in the classical near east. As opposed to less organized tribes on Rome’s European borders, the Parthians were a sophisticated culture of commerce and empire. The Parthians garnered significant wealth from its trade routes and its cities stood as some of the largest in the world. The entire diplomatic history between the two states is too complex. For that reason, we will focus on the stories of four Roman characters, three of whom ventured into Parthian lands. Regrettably, due to the scarcity of Parthian sources, the narrative will be told mainly from the Roman perspective. …

Setting the scene:

 … By 53 B.C.E. the Parthian Empire of the Arsacid Dynasty stretched from eastern Anatolia to the Indus River, a territory at least as large as the Roman Republic at the time. The Roman Republic, interestingly, had also been expanding at roughly the same timeframe. … Like how Parthian expansion crushed Seleucid power from the east, Roman expansion finished off the remaining western fragments of the Seleucid Empire in 65 BCE. Therefore, Rome and Parthia were two rising powers in the ancient world. It is at this timeframe that our stories begin. 

… However, the Roman senate itself was slowly losing control to three powerful men who came to dominate Roman politics: Caesar, Pompey and Crassus – together known as the First Triumvirate. It was Crassus who would ultimately bring war. … To Crassus, Parthia offered that opportunity for gloria.  

Crassus’ Defeat:

Crassus went forth with his plan and obtained the province of Syria. While people in Rome knew that Crassus was about to attack, a statement of war was never issued by the Senate, thus making Crassus’ invasion entirely a “private” war. In 54 BC, Crassus began his campaign with the taking of several cities in Mesopotamia. The Parthians did not immediately respond, possibly because their King Orestes had only recently been enthroned after a power struggle, and thus did not want to rush the formation of an army from the nobility. Eventually, after several skirmishes, a Parthian army under the general Surena of about 9,000 horse archers and 1000 heavy cavalry (Cataphracts) approached the city of Carrhae. Crassus marched toward his enemy with a much larger force of about 40,000 infantry and 3000 cavalry. As the armies met, the Parthian horse archers showed the Romans with arrows. Able to take no more, Crassus sent a detachment of his cavalry supported by archers and legionnaires under his son to charge the Parthians. This detachment was decisively destroyed by the superior cavalry of the Parthians, who then counterattacked carrying the severed head of Crassus’ son mounted on a spear. The Romans, although significantly outnumbering the Parthians, suffered heavy loses as they were shot down by the Parthian horse archers, whose arrows pierced Roman equipment at close range. Into night, the remaining Roman forces withdrew or fled from the battlefield into Carrhae. Crassus attempted to escape back to Syria, but was unable to find a way due to poor terrain intelligence. The Romans were intercepted and took refugee on a hill. There, the Parthian commander offered a truce to Crassus, stating that he did not wish for a full-blown war. However, negotiations failed, a fight erupted and Crassus was killed fighting his way out. In the end, only 10,000 Romans made it back. The rest were killed or captured by the Parthians. …  
The disaster at Carrhae was symbolic of the Roman Republic’s limitations in its expansion to the east. However, while Crassus’s story is probably the most well known in the Roman-Parthian wars, it is by no means the end. The invasion of Crassus dramatically altered the relations between the two states. Although the Parthians understood that Crassus acted on his own foolishness to wage war, they also understood the growing threat of the Romans. Two years after Carrhae, the Parthians under their Prince Pacorus invaded Syria. The Romans defended well but Pacorus returned in 40 BC with a larger force, this time with the rebel Roman Labienus at his service. Pacorus and Labienus defeated the Roman governor of Syria and overran the province. In addition, Pacorus placed his candidate, Antigonus, on the throne of the Jews. The news arrived at Rome in great embarrassment. The Roman general Ventidius was to lead the Roman forces in the upcoming battles.

…  After Caesar’s murder, Venditius served under Antony, who sent him to deal with the Parthian invasion.
Parthians defeated:

…Ventidius took a force of 11 legions, including a large number of slingers to defend against horse archery, for the Romans had learned that unsupported heavy infantry in the open were highly vulnerable. …  Unlike Crassus who ventured into open territory, the hilly terrain of the Taurus negated the Parthian strength in cavalry. Ventidius positioned his men on a hill with his infantry in a defensive position with his slingers while the Parthian cavalry poised themselves at the foot of the hill ready to attack. … Unable to beat back the Roman infantry in an uphill battle, the Parthians were routed. Pacorus withdrew but Labienus was killed in the battle.

…According to Plutarch, the Roman victory “fully avenged Carrhae.” With the Parthians driven out, stability was restored to the region. In Judea, Antigonus was driven out and the Roman-backed King Herrod was installed as ruler. In Rome, Ventidius was hailed Imperator and given a celebration of triumph, which he shared with Marc Antony, since Ventidius had been fighting under Antony’s command. However, from then on, no more is known about the service of Ventidius.

Marc Antony Defeated:

Following the campaign of his subordinate, Marc Antony decided to take matters into his own hands. In 37, Antony set out with 70,000 men to begin his own Parthian war. He took a route through Armenia and arrived in Parthian territory besieging the Parthian stronghold of Phraaspa. After skirmishes on the outskirts of the city, the two armies met in battle. The detail of the battle, which appears to be inconclusive, is not exactly certain. But with the lack of progress, Antony was forced to conclude his campaign with by withdrawing his army back to Armenia. Returning to Armenia, Antony’s army was harassed by the Parthians and met with disease. Only half of Antony’s army returned home.

Caesar Augustus’ “Diplomacy”:

In 31 BC, Antony was defeated by Octavian at Actium, thus marking the end of the Roman Republic and the beginning of the Roman Empire. The new era in Roman history, known as the Pax Romana (Roman Peace), also changed the nature of the Roman-Parthian relation. For the most part, the early “Roman Peace” that came out of exhaustion from the Roman civil wars carried through to their Parthian relations. The earlier defeats of Crassus and Antony still presented a dilemma. But Augustus did not want war with Parthia, even when presented the chance. Instead, by negotiation, Augustus was able to have the Eagle Standards lost by Crassus returned to the Romans. For the most part, relations between the two states took the form of “diplomatic maneuvering” rather than open war. Notable among the events is an Italian slave girl named Musa, who was sent by Augustus to the Parthian King.

[Setterfield note: Musa was the wife of Phraates IV and she poisoned him in the November of 2 BC when the Magoi were away traveling to Judea. Musa temporarily ascended the Parthian throne, then abdicated in favor of her son Phraateces by the murdered king].

Some of Musa’s sons moved their residences into Roman realms, where they became a group of exiled Parthian nobility that the Romans would later support as claimants to thrones. The situation is complicated by turmoil in Parthia, where the country was stuck by rapid succession of kings. The Romans were very much involved with the chaos in Parthia, where they attempted several times to support various claimants to the Parthian throne. However, the details are far to complex to pursue here. …

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The Roman–Parthian War of 58–63 was fought between the Roman Empire and the Parthian Empire over control of Armenia, a vital buffer state between the two realms. Armenia had been a Roman client state since the days of Emperor Augustus, but in 52/53, the Parthians succeeded in installing their own candidate, Tiridates, on the Armenian throne.
These events coincided with the accession of Nero to the imperial throne in Rome, and the young emperor decided to react vigorously. The war, which was the only major foreign campaign of his reign, began with rapid success for the Roman forces, led by the able general Gnaeus Domitius Corbulo. They overcame the forces loyal to Tiridates, installed their own candidate, Tigranes VI, on the Armenian throne, and left the country. The Romans were aided by the fact that the Parthian king Vologases was embroiled in the suppression of a series of revolts in his own country. As soon as these had been dealt with, however, the Parthians turned their attention to Armenia, and after a couple of years of inconclusive campaigning, inflicted a heavy defeat on the Romans in the Battle of Rhandeia.