[WP] It's 1933 and the Roman Empire survived and avoided its collapse. However, Adolf Hitler still rises to power in Germany, he then declares war on Rome. by Zorseking34

In 753 BCE, Rome was founded, or so the story goes. and by the beginning of the new millenium it had struggled up from its humble beginnings as a fishing village sheltered by seven peaks on the banks of the Tiber river into an imperial force to be reckoned with in Europe.
In those times, the Roman legions inspired fear and awe not only because of their discipline but because warfare, especially in transalpine Gaul, was composed largely of set piece battles where two disputating lords would select a location for their forces to meet and the army that broke ranks first was deemed the loser. There were injuries and even deaths but the aim in this trial by combat was to beat your opponent, not slay your enemy.
The legions were the first armies since the Assyrians to kill.
The role of the legionnaire was to close with the enemy and destroy him.
What came behind the legions was the rule of law for commoners, comparatively better sanitation, roads, viaducts, roman concrete, infrastructure, trade, markets, education, prosperity.
Then the cracks began to show. In 64 AD much of Rome burned but its citizen swore off wine and beer, replaced their antiquated lead pipes with new ceramic innovations and rebuilt Rome in what historians privately refer to as a 'flurry of urban renewal' and publicly they call the restoration period.
By the time Hadrian's wall was built in 122 AD the Roman govenors of the far flung provinces realized that the economies of scale which the Empire had enjoyed up to this point were based on a policy of constant outward expansion which everyone could see was unsustainable. If Rome failed to conquer the entire world, it would lose everything it had in the gamble.
So, with the same single minded determination with which Rome had raised its legions, it embarked on a lengthy process of re-inventing itself. Already, the garrisson legions were locally conscripted from their home provinces and the administrators were also primarily locals and a man could grow up speaking a proto-Germanic dialect and call himself a Roman. So Emperor Hadrian took the decision that he would rather have grateful trading partners he could influence than sworn enemies he could not.
Rome's empire, that stupendous wave that washed all shores, receded.
In 395 AD Rome was bounded by its two greatest cities, Rome itself and Constantinople in the east. Hundreds of years after Hadrian's visionary volte-face on territorial expansion, the cultural imperialism of the empire had pervaded all of Europe and North Africa. Rome was surrounded by friendly buffer states on all sides in an era of peace and economic prosperity which remains unsurpassed to this day.
The next few centuries were politically uneventful but there were many technological discoveries. Society evolved. Slavery was quietly abolished and women were given sovereign franchise. Rome adopt the modern Gregorian calendar.
In 1753 there were celebrations in Rome which were capped with a public demonstration by two teenage brothers of their new invention: a hot-air balloon.
They took the Emperor's body double up in the balloon for a publicity stunt and no one used one of the new fire wands to shoot him. Emperor Publius took this to be an auspicious sign.
In 1889, a young boy was born in Pannonia named Adolphus but in his life he went by the German spelling of his name. He was a mediocre artist but a gifted demagogue.
In 1914, there was social unrest in Germania and a minor rebellion in the north which the local German authorities were able to quash. A young hooligan named Adolf Hitler was sent to prison for two years where he wrote of his struggles against the local German authorities who he accused of having lost their Germanian-ness, of being totally under the cultural imperialism of Rome and he accussed Germania of being little more than a puppet state which he swore he would elevate to it's proper place: successor to the holy roman empire's long abandoned plans for total global conquest.
In 1931 Adolf Hitler joined the Pannonian Front.
In 1934 Adolf Hitler staged a bloody coup which was later named the 'night of the long lances.'
On August 2, 1934, Adolf Hitler became Tyrant of Germania
On September 1, 1939, Adolf Hitler invaded the state of Polonia which had a treaty with Rome.
On September 2, Rome declared war on Germania triggering a series of catastrophic events that finally broke the 1000 year old Pax Romana.
The ensuing conflict shook the foundations of civilization to such an extent that this conflict is now referred to as the Bellum Mundorum Unis.