Aminoff served as an officer in the Widow Queen's Life Regiment before being transferred to the King's Life Guard. He was promoted to Second Lieutenant in 1773, Lieutenant in 1775, Army Captain in 1777, Sub-Captain in 1781, and Captain in 1782. Finally, he became a Lieutenant Colonel in 1787.[1][2]
He took part in the Russo-Swedish War of 1788–1790. King Gustav III advanced Aminoff to the position of Colonel and Commander of the Pori County Regiment. He was elevated into the Pomeranian nobility.[1][2]
King Gustav III was assassinated in 1792 by nobleman Jacob Johan Anckarström. Gustav III was unpopular among the Swedish nobility because of his absolutism. Aminoff lost his status because he was a supporter of the King. Aminoff was viewed as a representative of the ancien régime.[1][2]
During the regency led by Baron Gustaf Adolf Reuterholm, Aminoff was not popular. The regency accused him of being involved in a conspiracy with the ambassador, Baron Gustaf Mauritz Armfelt. Aminoff was imprisoned for treason and sentenced to death, as well as to lose his honor, titles, and fortunes. However, his death sentence was commuted to a life sentence in 1794.[1][2]
King Gustav IV Adolf reached adulthood in 1796 and subsequently granted Aminoff his freedom, honor, titles, and fortunes. Aminoff returned to command the Pori County Regiment. In 1799, the king promoted Aminoff to the rank of Major General.[1][2]
In September 1808, a temporary truce was established between the Swedish and Russian forces. Aminoff was tasked with traveling to Stockholm to present the new conditions to the King. Following the meeting, Aminoff was granted the title of Baron, but he never introduced his title at the House of Nobility in Stockholm.[1][2]
After the Kainuu armistice agreement in March 1809 between Sweden and Russia, Aminoff returned to his Riilahti Manor in Bromarv, Finland. Despite the Russian occupation, Aminoff chose to stay in Finland. In 1809, Emperor Alexander I convened the Diet of Porvoo, which established the Grand Duchy of Finland within Imperial Russia, granting Finland autonomy as part of the empire.[1][2]
In 1810, Aminoff led a Finnish officer delegation to meet with the Emperor of Russia, Grand Duke of Finland, Alexander I in Saint Petersburg. Aminoff negotiated an agreement with the Emperor that allowed Finnish officers, the majority of whom were members of the nobility, to retain their salaries and estates.[1][2]
In 1811, Emperor Alexander I invited Aminoff to become a member of the Committee for Finnish Affairs in Saint Petersburg. In the same year, he was appointed as a Privy Councillor. In 1812, Emperor Alexander confirmed Aminoff's baronial title with a special document. In 1812, French emperor Napoleon invaded Russia. During the Napoleonic Wars, Aminoff acted as the chairman of the committee. He again acted as the chairman in 1814 because Count Gustaf Mauritz Armfelt passed away.[1][2]
Emperor Alexander I visited the Grand Duchy of Finland in 1819. During his visit, he elevated Aminoff to the rank of Count.[1][2]
In 1821, Emperor Alexander I invited Aminoff to become the chairman of the Committee for Finnish Affairs. Aminoff declined the Emperor's invitation.[1][2]
Instead, he became the vice-chancellor of the Imperial Academy of Turku in 1821, with the Crown Prince Nicholas I acting as the Chancellor. Aminoff was conservative, and both the Finnish and Russian elites opposed revolutionary ideologies at the university. The Great Fire of Turku occurred in September 1827, and Aminoff retired from his position in December of the same year. In 1828, the Imperial Academy was relocated to Helsinki, the new capital of the Grand Duchy of Finland.[1][2][3]
In 1823, emperor Alexander I granted Aminoff the title of president.[2]
Three Gustavians
Aminoff was one of the three Gustavians who were favorites of the assassinated King of Sweden, Gustav III.[1][3]
Aminoff, Johan Albrecht Ehrenström, and Gustaf Mauritz Armfelt received death sentences from the regency because the Armfelt Conspirary, but were all pardoned by King Gustav IV Adolf.[1][3]
Later, Aminoff, Ehrenström, and Armfelt became favorites of Emperor of Russia, Grand Duke of Finland Alexander I, and heavily influenced and shaped the Grand Duchy in Finland. All of them were appointed to high-ranking positions.[1][3]
