Lost Record of Trajan - why?

May 2018
One of the unfortunate things about "Rome's Greatest Emperor" is that we know relatively little about his military campaigns. We know much of Caesar and Scipio Africanus due to surviving works such as the Commentaries and writers such Polybius.

Trajan's historical reputation has the rare distinction of being high among historians for over a thousand years: he is still generally regarded as Rome's greatest Emperor. In medieval times, it was even said that a Pope resurrected him and baptized him!

If Trajan has such a "rockstar" reputation throughout history, how did so many records of his campaigns become lost? Trajan wrote his own Commentaries (probably following Julius Caesar's example), but they have become lost.

Trajan was no obscure Roman emperor: he has been considered the greatest Roman emperor for pretty much the entire period of history since his death. I find it somewhat odd that of Commentaries of the Dacian War, only fragments survive, given that works survive by more ancient historical figures who would be "lesser" than the widely-accepted "Greatest Roman Emperor".
Oct 2018
It's worth noting that Trajan was dubbed Optimus Princeps by the senate of his day because of his good relations with that body, not because of, say, military accomplishments (at least not his Parthian campaign, which happened at the end of his reign). Trajan was a breath of fresh air for the senate. He made a point of having good relations with them, acting with clemency and not conducting prosecutions against senators. In this way, he won their loyalty, creating a point of difference between himself and most of his predecessors (Tiberius, Caligula, Claudius, Nero, Domitian). Historians have also come to assess him pretty well because a) the empire reached its greatest territorial extent through his campaigns in Dacia, Arabia and Mesopotamia (although the Mesopotamian conquest was quickly abandoned by his successor Hadrian), and b) he is among the so-called Five Good Emperors of the second century, who ruled the empire during a time of peace and prosperity, and who passed power to meritorious successors through adoption (although his wife was actually accused of fabricating Hadrian's place as Trajan's successor). Of these five he is also the first truly great one, since Nerva isn't really all that impressive.

That being said, it is indeed odd and unfortunate that we do not have better historical texts on the reign of Trajan. Prominent historians and biographers were writing during his reign (Tacitus, Suetonius, Plutarch), but Roman historians tended not to write about the life of the emperor they are writing under, since one cannot be objective when the wrong words could lead to exile or death. It was just not the normal practice. A notable contemporary text on Trajan is the Panegyric of Pliny the Younger, but being a panegyric (a speech of praise) that was spoken before Trajan by Pliny in order to thank him for being awarded a consulship, it is not a particularly reliable text, and it predates his campaigns against the Dacians and Parthians anyway.

The most notable historian to cover Trajan's reign is the fourth-century historian Ammianus Marcellinus, who sought to pick up where Tacitus left off, covering the years 96 to 378. Unfortunately, what survives of his history only covers 354 to 378, the part of his history that, based on the number of books apparently written, is evidently the most detailed part of his history (naturally, since he was writing about events in his own times). This means that Ammianus' treatment of some of Roman history's greatest emperors (Trajan, Hadrian, Marcus Aurelius, Aurelian, Diocletian, Constantine) is now lost. Some have postulated that Ammianus' style of highly detailed history became somewhat antiquated as summary histories and chronicles became more popular, and that this may help explain why the early part of his history has not survived.
Last edited:
Sep 2013
Ontario, Canada
That we have anything at all from authors who wrote things down 2000 years ago is nothing short of a miracle. All ancient documents are copies because the originals would've been on papyrus or wax tablet or felt parchment that would've crumbled, and those copies would've been in danger of decay after a few centuries themselves. And it wasn't a cheap thing to make a copy, either. It had to be written out again by hand on fresh paper, which only the wealthy would order on a whim. This meant that the popular writings were saved while the rest faded away. So therefore we only have the responses of Trajan to Pliny the Younger, acting as a Emperor advising his provincial governor, which is what people apparently thought he was worth reading about rather than the military adventures in his Commentaries.

Lord Oda Nobunaga

Ad Honorem
Jan 2015
Ontario, Canada
A lot of the texts in this period suffer from issues of being contemporary work. Hard to know what was happening during an actual event and they didn't really have the benefit of hindsight. Not only in Trajan's time but also an issue for the historiography concerning Hadrian, Antoninus Pius and Marcus Aurelius. All of these Emperors also clamped down to prevent people from sowing dissent. While they did have decent relations with the Senate that was not a green light to start writing everything that occurred. Hadrian basically carried out purges of the army and senate to secure his succession and while life under Hadrian was good there must have been a creeping fear over the aristocracy and low born bureaucrats which would have written histories or letters. For Hadrian at least we have his autobiography of which pieces have been preserved, but much of our current knowledge comes from the huge amounts of material remains from Hadrian's vast construction projects. Other sources refer to the contemporary writings as well, so we can pick out the bits and pieces. But the important part is that there just weren't that many contemporary writings produced at the time for whatever reason, even ignoring censorship. The Late Republic has far more written works associated to it in general.

It seems that you were asking about the Parthian campaign under Trajan?
From these fragments and hindsight in the reign of Hadrian... it does appear that Trajan's Mesopotamian campaign was largely unsuccessful, ultimately. It is true at least that Trajan managed to clear out the Parthians from Armenia and Mesopotamia. What occurred afterwards was a massive revolt across Mesopotamia and discontent across the Middle East, leading to uprisings by the Jews and other locals. At least in the case of everyone else in Egypt and Syria they must have been angered by the tax burden and having to support a massive army in their territory. This quickly led to the army getting bogged down and a supply problem ensued (maybe not as imminent or dramatic but still a problem). Around which time Trajan was attempting to besiege the desert city of Hatra which also led to the army being bogged down and withdrawing. There is also a sense that Trajan was old and infirm and wished to return to Rome, however that wasn't so much the reason that the army itself withdrew. Trajan opted to hand over Lower Mesopotamia (Ctesiphon) to a Parthian prince which defected to him and had the army occupying Upper Mesopotamia. Then when he left for Rome he left Hadrian, who was governor of Syria, in charge of the army. At the same time he had legion and cohorts from other provinces sent to put down the rebellions in the provinces. But it appears that Hadrian's concern was losing too many men in a foreign counter insurgency campaign because as soon as Hadrian was declared Emperor he withdrew his forces and sent legions to bolster the already victorious forces in Syria and Egypt (to prevent more insurgencies likely).

That was not the end of the Parthian troubles since the puppet ruler in Ctesiphon was defeated by a Parthian counterattack from Iran. Then naturally, then Parthians took back Upper Mesopotamia. Hadrian must have assumed that the Parthians would always carry out a counterattack and so did not want to be caught on his back foot. Then in the 120's the Parthians amassed an army near the Euphrates but Hadrian dissuaded them through diplomacy and ordering legions to be mobilized to fight off the potential invasion. Maybe in hindsight it made sense to at least keep Upper Mesopotamia but Hadrian was more worried about overextending his army than he was about Parthian military invasion. Mesopotamia would require massive supply lines, huge tax burdens to the east and large garrisons to control the area. That is disregarding how many more troops would be required to fight off a Parthian invasion. All those troops would be required in other places since the Empire was very overextended at the time. What is more Hadrian's reign saw an attempt to keep the legions in peak conditions. Which implies a loss of soldiers and veterans, if not from the Parthian campaign then probably from old age. Hadrian even resorts to hiring foreign mercenaries as part of a permanent force. During the reign of Marcus Aurelius there is a critical lack of professional soldiers. Which implies that soldiering was no longer a popular profession for the average person and since times were prosperous under the Good Emperors, a lot of the populace would rather find employment under the civilian sector.

Also, in the reign of Marcus Aurelius the Parthians attack again and Marcus Aurelius did not decide to take over Upper Mesopotamia either. Most likely for the exact same problems. Plus occupying Upper Mesopotamia probably would encourage further invasions because the Parthians would want their territory back. A Parthian attack would probably just lead to any forces there being cut off, when dealing with the Parthians required almost a total mobilization from legions across the East, Egypt, the Danube and on occasion the Rhine. Furthermore there is no best area to take across that flatland and desert region since taking or campaigning any amount of land is only aided by the flow of the Euphrates and going as far as the Tigris wasn't conducive since the Tigris was its own farther network. If anything it would make sense to only occupy the cities across the Euphrates, maybe even go as far as the Khabur River. It isn't clear if this is what Marcus Aurelius decided to do or not, or if he withdrew completely back across the Euphrates.
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