The history of the post-PoD world in Shadow of the Eagles is told in several different pieces, each parts forming a whole. As there were the Dark Ages, the Renaissance, the Industrial Age, and so on in OTL, the world portrayed in Shadow of the Eagles is largely broken into several different eras. While these eras obviously revolve around western history, the history of the east, as well as that of pre-Columbian American history, are covered as well. The names of these eras were coined in relatively modern times, using Latin names to describe each section of history.
It is assumed that the use of these Latin words to describe portions of history began in the 19th century, with the terms becoming popular within decades. While the definitions of each era varied in terms of year begun or ended during the early days of the usage of these terms, most historians today agree on when each era began and when each era ended within a small margin.
The term 'Tempestatum,' meaning 'storm,' was one of the first terms coined to define the era immediately following the year 450 AD. While 450 AD does not mark a particular event, it is close to several key events, such as the disastrous Council of Chalcedon, the invasion of Attila the Hun into Western Roman Gaul, and the death of Emperor Marcian. Moreover, this 450 AD is when the universe started to diverge from our own, yet modern historians of this ATL obviously had no way of knowing. While the 450 AD bookmark has been used by historians, in the past the beginning of the Tempestatum was marked by the Council of Chalcedon and murder of Marcian in 451 AD. This bloody year marked the beginning of an era of change in Europe.
As the Tempestatum continued, the Eastern Roman Empire was thrown into utter disarray. In the meanwhile, the West was able to thwart the Hunnic invasion. Following these events, general Flavian Aetius thwarted a plot to kill him by Valentinian III, eventually leading a military coup against Valentinian III. With Valentian ousted and the Theodosian Dynasty crushed, Flavian Aetius (Aetian I) established the Aetian Dynasty. This dynasty of Roman Emperors placed an emphasis on the military of Rome, ultimately defeating several barbarian invasions under the leadership of Aetian I alone.
In 461 AD, Aetian I died, placing the Western Roman Empire under the control of his son Gaudentius I, whose actions in the completion of the Aetian Reforms, allowed the Western Roman Empire to form massive counterattacks against the Visigoths in Spain. In the meantime, the Eastern Roman Empire struggled with the Ostrogoths and the Hunns. Their repeated losses, in addition to the ensuing chaos after the Council of Chalcedon, led to a wave of Eastern Roman forces joining the Western forces. This strengthening of the west actually allowed Gaudentius to rout the Visigoths from Gaul. Though he was forced to sacrifice territory in the Hispania, Gaudentius was able to hold onto southern Gaul. In 469, he began a counterattack of the Vandals in Sicily and Sardinia before retaking land in Tripoli. In the meantime, rebellions in the East led to further desertion into Western Roman territory.
The Aetian Dynasty continued to rule the Western Roman Empire until 538 AD, when Carpilian was slain in Valentia without an heir. The loss of the Aetian Dynasty marked a period of territory loss for the Western Roman Empire, holding the barbarians back at the Alps and ruling from Italy in a period of isolationism, with brief military campaigns of varying degrees of success along the Adriatic and Ionian coasts. As the Western Roman Empire worked to establish its borders, the infighting of the Eastern Roman Empire led to an opportunity by the Sassanids to take Eastern Roman territory in the Levant.
While both Empires survived the Tempestatum, their loss of power marked an era of change in Europe. Despite the efforts of later Western and Eastern dynasties to restore parts of the Empire, spreading both Latin and Greek culture, the era of Roman power in Europe was over. <more to be added>