Alessandro Napoleoni was born on Sardinia, Italy in 1786. He joined the Italian army only sixteen years old, and soon rose through the ranks. As a captain, he participated in the Italian conquest of Cuba.
In 1810, then a major, he was promoted colonel by king Gioacchino of Italy personally. More important however was the fact that the old king who liked the young officer decided to make Alessandro his successor, just like the adoptive emperors of Rome, since he was the last one living of his family and feared that his kingdom might break together.
In 1823, practically immediately after king Gioacchino had died, he declared himself New Roman Emperor Alessandro I. He planned to unite the lands of the old Roman empire (in Western Europe at least), but also thought about new colonies.
1824, the Imperial-Catholic church was founded, of which the New Roman emperor was the head. He used the church as a tool to bring the former French and Spanish colonies better under his heel. Priests who denied the oath on his person were expelled or incarcerated. In the same year, Germany and New Rome made a treaty of friendship.
In 1825, the Spanish lands in South Atlantis were occupied by New Rome. Now however, the empire was lacking money. So emperor Alessandro attacked and conquered the Inca empire Tawantinsuyu during 1826-29. Their gold and silver mines from now on worked for the New Roman Empire.
1827, a New Roman expedition returns from India, further spurning the interest in the subcontinent. Having learned that there exist cults in India which use to murder for their gods, like Kali, Alessandro started thinking about using them for his purposes.
In 1837, Texas was added to New Rome. And 1838-40, Morocco was conquered by New Rome after a Muslim uprising there. The (fled) Spanish royal family was exiled to Braseal. Alessandro had the old Holy City of Kairouan (Tunisia) re-secrated for the Muslim pilgrims.
The European powers
Emperor Alessandro knew that France was too busy holding down occupied Spain and defending against Germany. So he took a closer look on Britain, the only other surviving colonial power instead. This also had to do with the fact that he felt insulted by king Philip who still claimed the meaningless title of Holy Roman Emperor, decades after the end of the HRE.
During 1832-36, the Anti-British War of allied New Rome, Germany, German Atlantis and Canada took place. Unexpectedly, the Imperial Navy proved to be stronger than the Royal Navy, thanks to the numerous fights against the Spanish Navy-in-exile. In the peace of Roma Nuova, Britain had to cede Haraldsland to Canada and its lands in South Atlantis, which were divided along the Tropic of Capricorn: Braseal went to New Rome, the Germans received Argentine as a place for settlement (from now on, more often called Argentinien). Patagonia, being uninteresting for the victors, became the independent native state of Aymaria.
When Russia diplomatically clashed with Hungary in 1834, emperor Alessandro feared Russia invading Hungary at the wrong time. So he suggested the Hungarian Division instead: Austria went to Germany, Croatia to New Rome, Transsylvania became a Russian protectorate. New Rome also acquired most of OTL Slovenia (which had been once Austrian, until Austria was inherited by Hungary in 1816), so Germany was cut off from the Adria.
The emperor developed New Rome on many levels. During 1832-39, the Suez Canal was finally built.
After anti-Jewish pogroms in North Africa, a delegation of rabbis approached the emperor 1835. He offered the Jews a home at the Sinai, as close to biblical Israel as possible without moving right in, to form a buffer against the Persian empire and to guard the Suez Canal. This marked the beginning of the Jewish state Judea. (This was not completely un-selfish: The Jewish traders now could be replaced by Italians, thus strengthening their influence in the empire.)