Ages Of the Federation is a new series of total conversions to Sins Of A Solar Empire: Rebellion starting with "The Four Years War". The first mod in the series takes place between the Enterprise and Original series eras, focusing on the conflict between the early Federation and Klingon Empire. A Resurgent Romulan Star Empire, angry and still licking its wounds after its defeat to the federations waits in the shadows, ready to take advantage of a misstep by either the warring powers.
In the days before the Battle of Axanar, the Klingons sweep aside the defences of the Vulcan colony world of Trilan, crippling a D'kyr-class star cruiser and reducing the small orbital research outposts to rubble. With the Federation's inner worlds increasingly vulnerable, the Klingons are within sight of victory.
Since the collapse of the Vulcan Command, the Vulcans had abandoned their policies of imperialism and re-embraced the doctrines of pacifism laid out in the philosophies of Surak. Much as they had in the Earth-Romulan War, the Vulcans chose to keep their military contributions to a minimum during the Four Years War, instead lending their formidable scientific prowess to the war effort. Vulcan scientists and engineers were instrumental in the development of improved sensors, life support and propulsion systems. For their part, the Vulcans were content to leave weapons technology in the hands of humans and Andorians. Even so, as the Klingons advanced the Vulcans diverted a number of their starships to protect their colonies most at risk - pacifism, after all, ought not rule out self-defence.