Coalition of Galactic Defence

The Coalition, formally the United Coalition of Galactic Defence and Preservation, was a military alliance formed in the wake of the Terran entry into the Great War, with the explicit intent of defeating the Terran Federal Republic militarily. Its founding members were the Surben Republic, the Ur-Han, the Dermkha Republic and the Tefnir Republic. The Mirdesh Confederacy joined in 2640.
The member states of the Coalition were initially in a informal alliance against the Ur-Han Empire since the 2610s. The war between the allies and the Empire in the First Phase of the Great War was a stalemate with many backs and forths. The Terran entry into the war against the Empire in 2636 allowed the allies to decisively defeat Imperial forces within a year. The allies were proclaimed the legitimate governments within the ex-Imperial territories. 
Despite the Terran war efforts initially being primarily aimed at the Ur-Han Empire, the Terrans fought against the allies and the new Ur-Han government. The year of 2637 was marked by minor skirmishes, but the Terrans launched an all-out offensive in November. In 2638, the Terrans decisively defeated allied forces at the Battle of Kojim and occupied much of the Dermkha territories and entered Surben space. In response, the allies created the Coalition on the 26th of January 2639 so as to unite against the Federation. 
The same year, the Federation proclaimed the Dermkha Protectorate. Despite the Coalition's efforts, the Terrans were able to push deep into Surben space and occupy all of Tesrat space. Following the proclaimation of the Tesrat Protectorate in 2640, the Mirdesh Confederacy, which had been aiding the Coalition already, officially joined it. The Mirdesh intervention was able to push back the Terrans to the edge of Surben space and hold them back elsewhere. 
The Coalition's success was bestfelt from 2640 to early 2646, a period during which the Terrans were stopped and pushed back out of Surben and Ur-Han territory, before the war reverted back into a stalemate. Its effectiveness decreased over time however, as disagreements between the allies became important again, partially due to Terran covert operations. Ultimately the Coalition would be ineffective at stopping the Terran offensives thrroughout 2646 and 2647, when it was nearly pushed out of Ur-Han territory. The Coalition was disbanded by the Treaty of Mars.