Treaty of Mars

The Treaty of Mars, formally the Treaty of Cessation of Hostilities and Future Cooperation between Galactic Nations, was a peace treaty marking the end of the Great Galactic War. It was signed on October 19th 2650, over three years after the end of hostilities. It was signed at the peak of Olympus Mons on Mars, which earned it the nickname of Olympian Treaty. 
The Treaty definetly ended all hostilities between all signatories and established the Union of Cygnus-Orion, charged with avoiding a repetition of a conflict on such a scale. It also formalised the various border changes of the war: the Surben Republic annexed the Surben and Telom duchies; the Ur-Han Kingdom was recognised as the legitimate Ur-Han government in the Ur-Han duchy; the Tesrat Republic was recognised as the government of the Tesrat duchy; the Dermkha duchy, reorganised into the Dermkha State, became a Dominion of the Terran Federation. Importantly, the Treaty opened up the markets of other nations to the corporations of the Terran Federation, but the Federation was allowed to keep a protectionist economic policy. The Treaty also established the Terran occupation of the Ur-Han Kingdom. 
Its significance can not be understated, as the Treaty laid the groundwork of the geopolitical state of known space, making the Terran Federation its pre-eminent state and definitely removing the Ur-Han as a great power. The Treaty was also the basis for the short lived Terran-Alien Cold War as well as the 2666 Détente. The Treaty of Tefnir, signed in 2671, was largely a successor to the Treaty of Mars and improved it, setting the basis for the unprecedented cooperation between nations seen since.