He advanced claim to the throne of Kartli and Kakheti after the death of his half-brother George XII in 1800 and opposed the Russian annexation of Georgia until being apprehended and deported in 1805 to Tula.

At the time of an invasion by the Iranian army of Agha Muhammad Khan in 1795, he was headquartered at Gori and did not take part in fighting which devastated Heraclius's capital, Tbilisi.

In 1791, at insistence of Queen Darejan, Heraclius II signed a testament, requiring the king's successor to pass the throne not to his offspring, but to his eldest brother, thereby making Iulon the second in the line of succession, behind his half-brother Crown Prince George.

[3] After Heraclius's death in 1798, the ailing king George XII abrogated this new law of succession and obtained from Tsar Paul I recognition of his son, David, as heir-apparent on 18 April 1799.

Iulon, Vakhtang, and Parnaoz blocked the roads to Tbilisi and attempted to rescue their mother, Queen Dowager Darejan, who had been forced by George XII into confinement at her own palace in Avlabari.

The arrival of additional Russian troops under Major-General Vasily Gulyakov in September 1800 in Tbilisi made George XII's position relatively secure, but the unrest continued.

Iulon, his son Leon, and brother Parnaoz were invited to lead the movement, but the princes failed to make their way to the rebellious areas and fell back to Imereti.

A Russian detachment, commanded by Captain Novitsky and guided by the Georgian prince Giorgi Amirejibi, hurried from Tskhinvali and surprised Iulon's sleeping men at the Imeretian border.