The United States Navy is one of the primary military branches of the United Earth Government military that was formed the day the UEG was formed on May 7, 2219. As of June 21, 2401, the USN contained about 389 ships, just over 80% of humanity's overall space-faring naval forces. After the First War of Continuation, many more nations on Earth managed to build capable warships, including Brazil, Mexico, Egypt, Poland, Australia and many others, decreasing the USN's total control of the UEG navy down to about 70%.
The military hierarchy of the USN is similar to what the US navy was when it roamed the seas of the world about four centuries before the meeting with the Unity of the Core Worlds. Once reaching the rank of Captain, where one will be able to receive overall command of (at the most) a cruiser-class vessel, will be a part of the majority of commanders of the fleet. However, once being promoted, they will be promoted to High Captain, where they will be able to participate in the Naval Council, lead by Fleet Admiral Kyle Seam and involving some of the most important people in both the United States Navy and in the naval forces of the UEG as a whole.
The United States Navy was, as of June 2401, organized into six separate fleets, operating at their own different stations.
- Fleet Admiral Ryan Walker commanded the 1st Fleet from his flagship, the carrier USN Maine, above Earth.
- Fleet Admiral John Harper commanded the 2nd Fleet from the carrier flagship USN Boston, operating from the Galileo Stations orbiting Saturn.
- Fleet Admiral Hector von Brown, a transfer from the growing German Navy, was commanding officer of the 3rd Fleet, operating from his flagship USN Otto von Bismarck over Mars.
- Fleet Admiral Zachary O'Brien's 4th Fleet and his carrier USN Los Angeles bolstered the 1st Fleet's garrison over Earth.
- Fleet Admiral Michael Reed led the 5th Fleet over the Voyager Stations at Jupiter from the USN Dallas.
- Fleet Admiral Preston Smith commanded the 6th Fleet, known as the "Mobile Fleet" as it constantly shifted stations, but in June 2401 it was located over at the Herschel Stations in the inner asteroid belt.