The ruling House of Danis took to the idea of a Constitutional Monarchy and ordered that a constitution be drafted in 1790. The idea was welcomed on the Mainland as a promise of unity, but was rejected by "True Monarchists" in Treyland and Nordanis. The Royal House of Bunbenic in Treyland and the Northern House of Danis outright rejected the proposal and began official protests after the 1807 adoption on the Constitution of the United Kingdom of Dannunifius. The True Monarchists believed that the Constitution was the first step in limiting the power of the monarch and would eventually lead to the elimination of the monarch as Jamsterdavania had done in breaking with Deutscheslavania in 1676.
Treyland made the initial protests in the Edicts of Monarchy presented to the Crown at Sacia in September 1807. The Principal Crown Protectorate Janos Degarto rejected the Edicts. In return, the Treyland Principality of Carlone rejected the Dannunifian Crown's decision to Crown Stefan Donox King of the New Constitutional Monarchy. True Monarchists assumed command of the Royal Danis Army of Treyland stationed on the island and marched on Carlone on May 4, 1808. Archduke Trevor Bunbenic assumes the Principality and is installed as the First King of Treyland by Archbishop Donaldo Cardinal Degrasse. Bunbenic declares the Royal House of Treyland as a true monarchy.
A two-year war is waged between Treyland and Dannunifius. Treyland sought help from abroad but was rejected by Jamsterdavania and Stefanfang. Other nations were slow to recognize Trelandic independence. Riosland, a fellow revolutionary Monarchy, recognized it in 1815 and was mutually recognized by Treyland. Stefanfang agreed to recognize it if it agreed to remain neutral in its dealings with Riosland and Stefanfang and refrained from aiding Riosland in the First Rios/Stenfine War also in 1815. Vickberg recognized Treyland in 1816. Veravania established an embassy in 1816. Jamsterdavania recognized an Independent Treyland as part of the Jamsterdavanian-Rioslandic Pact of 1817. Dannunifius finally ceded Treyland on June 18, 1818 when it recognized Riosland as part of an early Alliance between North Catlantic powers. This officially ended the war with a Treaty of Carlone that established a mutual non-aggression pact renewable at five-year intervals.