The Treaty of Union is an agreement between the Kingdom of Brunant and the Principality of Roseland that led to the union of the two countries. It entered into force on 18 August 2011. Initially, the parish would be named Aurora Parish instead of Roseland Parish, but this never happened. The treaty also indicates the transfer of power to the President of Brunant, but this function was abolished in 2014. These provisions in the treaty were changed, replacing the President with the Prime Minister.
- The Principality of Roseland will join the Kingdom of Brunant as its newest parish and its official name will be changed to Roseland Parish.
- The Principality of Roseland will surrender its full sovereignty to Brunant and adopt the Constitution of Brunant as its new supreme legal authority.
- The King of Brunant will become the official head of state of Roseland and represent it to foreign countries.
- The President of Brunant will take full control over Roseland's foreign policy and defence and will have the right to intervene in Roseland if necessary, but the people of Roseland will retain their autonomy over local administrative matters.
- The Principality Government will be dissolved and all government powers will be transferred to a democratically-elected parish representative, who will be directly responsible to the Congress.
- The Prince/Princess of Roseland will retain his/her title as an honorary title.
- The negotiation process begins: 16 August 2011
- The Brunanter Congress ratifies the treaty: 18 August 2011
- The President of Brunant signs the treaty: 18 August 2011
- The Princess of Roseland signs the treaty: 18 August 2011
- The King of Brunant signs the treaty: 18 August 2011
- The treaty enters into force: 18 August 2011
- President Gert Henneman of Brunant: HORTON11 18:01, August 18, 2011 (UTC)
- Princess Davina of Roseland: Davina Rose 17:57, August 18, 2011 (UTC)