Artei 20th was of the race of Star Elves, the son of Artei 19th, and the last Imperial Sovereign. When he inherited his position in Year 13,091, he already realized that the Star Imperium was doomed. He appointed Freethinkers as Imperial Viceroys and as Prime Minister. He fruitlessly tried to negotiate a peace treaty with the Rebel Alliance for nine years.
Finally, the moon of Alfheim was invaded by Rebel Alliance forces in Year 13,100. Artei 20th, pressured by Rebel Alliance leaders, pushed through a radical amending of the Fundamental Laws through the Imperial Parliament which transferred Parliament's legislative powers to the United Planets Assembly, abolished the monarchy of the Imperial Sovereign, and established the government of the United Planets. He gave his assent to this radical legislation, then retired from politics.
Artei 20th is remembered by politicians and historians of the United Planets era for ushering in a truly democratic intergalactic government an for being a political pragmatist.