Optimus Trajan

-When Trajan returned from Dacia, he built a bunch of new stuff including triumphs, a forum, baths, and a new harbor built in 113 AD.
   -Also built a new highway from Beneventum (modern-day Benevento, Campania) to Brundisium (modern-day Brindisi, Apulia) because the Appian Way (which led from Rome to Brundisium through Beneventum) was such a clusterfuck.
      -Other roads were built upon, improved, and expanded as well, including bridges designed by the genius Apollodorus.
         -Unfortunately in later centuries these roads and bridges would allow for the barbarian hordes to travel throughout the empire with startling speed...
-A lot of what we know about Trajan comes from his colleague, the historian Pliny the Younger.
   -Born in 61 AD to an Equestrian family.  Father died when he was young.
   -Educated by Lucius Verginius Rufus (remember him?  He was the governor of Germania Superior during the end of Nero's reign and had stayed loyal to Nero and crushed Gaius Julius Vindex's rebellion in Gaul in 68 AD, and had also been so popular with his troops that they had been ready to straight-up declare him princeps!  Of course, Verginius had refused to betray Nero).
   -Pliny the Younger eventually moved to Rome and continued to be educated, but this time by his famous uncle, the naturalist (and writer, philosopher, former military commander, and personal friend of Vespasian) Pliny the Elder!
      -Unfortunately, Pliny the Elder was killed in the eruption of Mount Vesuvius in 79 AD (died in Stabiae (modern-day Castellammare di Stabia, Campania)).
         -Left all of his property and wealth to Pliny the Younger, who was also to be posthumously adopted as his son.
   -Thus, Pliny the Younger quickly moved up the cursus honorum, and eventually became a well-respected lawyer, senator, and administrator.
      -During this time he also be came good friends with the historians Tacitus and Suetonius, as well as Trajan.
         -He was so trusted by Trajan that in 110 AD, Trajan sent Pliny to go manage the province of Bithynia, which was falling apart due to shitty administration.
            -It took Pliny two years to clean up the situation, but during this time Pliny and Trajan sent each other letters which we still have today and gives us valuable insight as to how the empire managed all of its provinces, as well as Trajan's philosophy of how shit should be run (based on common sense, tradition, and Trajan's own intuition/judgement).
               -One interesting tidbit with these letters involved discussion of what to do about the mysterious new cult of Christianity, which was quickly spreading throughout the eastern half of the empire. 
                  -Governors across the empire were confused about what to do with Christians.  Christians refused to worship the Roman gods or accept the divinity of the Roman emperors, and many governors feared that the cult would foment eventually foment civil unrest wherever it had a significant presence.
                     -There was a greater fear that the cult would eventually encourage rebellion.  Obviously, it was illegal in the empire to form independent political parties or movements.
                        -However, Trajan encouraged caution about persecuting alleged Christians, especially because using paid informants or rumors would just make the governors more tyrannical and create more political unrest, so he made sure to stress that alleged Christians should be given a fair trial, but always be given the chance to renounce their faith.  However, if they refuse to renounce Christianity, they must be punished! 
                        -The problem of what to do with Christians would be a pain in the ass for administrators for the next 200 years (until Constantine converts!)
-Anyway, Trajan was thus far proving to be a badass ruler, and was given the honorific title "Optimus" ("the Best").
-110 AD- Meanwhile, more drama was going down in Armenia.
   -As we may remember, Rome and Parthia shared hegemony over the kingdom.  The Parthians got to choose the Armenian king, but Rome had veto power.
      -Anyway, when King Sanatruk (AKA Sanatruces) of Armenia died in 110 AD, Parthia chose a dude named Axidares (AKA Ashkadar/Exedares/Exedates), the son of Pacorus II (a former Parthian king) and nephew of Osroes I (the Parthian king at this time), to replace him.  However, Parthia had not consulted Rome about this and just had Axidares enthroned without Rome's consent.
         -While Rome actually had no problem with Axidares, they were pissed off that Parthia hadn't consulted them about this, considering them to be a sign of grave disrespect (and, by extension, a possible invitation to war).  So, hoping to avoid war with Rome, Osroes I had Axidares deposed and replaced by Axidares' brother, Parthamasiris (AKA Partamasia / Parthomasiris).
            -It probably also didn't hurt that Osroes I had considered Axidares to be a shitty ruler, anyway.
            -Anyway, because the Romans were pissed about this whole situation, Trajan declared war on Parthia! 
               -Of course, it's also possible that Trajan just wanted an excuse to pick a fight with Parthia :)
-113 AD- Trajan invaded Armenia, and by the following year the Romans had crushed the Armenian defenses and had Parthamasiris dethroned (and possibly executed).
   -Armenia was then officially annexed as a Roman province.
   -Of course, Trajan didn't just stop here, and continued to wage war against the Parthians.
-115 AD- Trajan invades Mesopotamia (Parthian territory).
   -This was also a great time for Rome to invade, as Parthia was kind of fucked up during this part of its history due to political infighting and just not having their shit together.
-116 AD- Mesopotamia was officially annexed as a new Roman province.
   -One of the most important cities conquered by Rome during this time was the ancient city of Babylon (modern-day Hillah, Iraq).
   -The Romans then sailed along the Tigris and Euphrates rivers, eventually caputring the Parthian capital Ctesiphon (outside of modern-day Baghdad, Iraq).
   -The Romans eventually made it so far downriver that they soon arrived at the Persian Gulf, where Trajan famously stated that he was saddened because he wouldn't be able to see the Romans march into India (like Alexander the Great) because he was too old that point. 
      -All of this was annexed into the Roman Empire. 
      -Osroes I was then dethroned and replaced by his son, Parthamaspates, as a puppet king.
         -It seems likely that Trajan's ultimate goal was to just straight-up conquer the entire Parthian Empire and annex it into the Roman Empire!
-Of course, the Parthian Empire was pretty big, so even though the Romans had taken over Ctesiphon the Parthians still hadn't given up!
   -An army was raised by Mithridates IV (brother of Osroes I) and his son Sanatruces II, and they began launching attacks against the Romans, although they were ultimately defeated.
   -Also, a serious revolt in Judea was also getting worse, so Trajan decided to retreat and consolidate his forces.
   -Unfortunately for Trajan, he was getting old and it was hot as fuck in Mesopotamia, so he suffered from heat stroke.  Realizing that he would probably die if he continued to personally wage war in Mesopotamia, he decided to have the legions stay and try and pacify Mesopotamia while he himself returned to Rome to recover.
      -However, the long trek had take a serious toll on Trajan's health, not to mention the stress of running the empire and the seemingly endless military campaigns, and so he died in the city of Selinus, Cilicia (modern-day Gazipaşa, Antalya in south-central Turkey) :(