The exploratory and defence service of United Earth in the 22nd century, which launched the first warp five starship and later became the core of the Federation's Starfleet.
United Earth Starfleet is the organisation Jonathan Archer serves in Enterprise. Based in San Francisco, it grew out of the Warp Five programme begun by Henry Archer and Zefram Cochrane, and for decades its ambitions were held back by cautious Vulcan advisers.
In 2151, in Broken Bow, Admiral Maxwell Forrest sends Enterprise NX-01 on its first mission, followed later by Columbia NX-02 under Erika Hernandez. Its officers use naval ranks, and its ships are far slower and more lightly armed than those of later centuries.
The service fights the Xindi crisis with help from the military's MACO troops and stands at the centre of the coalition talks of 2155. With the founding of the Federation in 2161, shown in These Are the Voyages, it gives way to the Federation Starfleet.