Gustave-Achille Laviarde was born on November 7, 1841. He married Dona Maria Elisa Octavia Guery on May 20, 1876. Upon the death of King Orelie-Antoine death on September 17, 1878, Achille became king of Araucania and Patagonia.
During the reign of King Achille I, the functions of the Council of the Kingdom and the Council of State were performed by the Privy Council. The Honorary President of the Privy Council was Baron Anatole Arthur Textor de Ravisi. The President was Dr. Antoine Cros, Duke of Niacalel, who would later be King Antoine II. Eugene Mahon de Monaghan, among others, was a member of the Council.
Achille died March 6, 1902 and left no children. In his will, he named Antoine Cros as his successor. Achille I is buried in the Tourtoirac cemetery, next to Orelie-Antoine. Achille I reigned from September 17, 1878 until March 6, 1902.