The Colonial Fleet is either the, or a major part of, the Colonial military, under the jurisdiction of the Ministry of Defence. The fleet operates in tandem with the other main branch of the armed services, the Colonial Marines.
The Fleet was presumably based at Picon Fleet Headquarters, and was under the leadership of Admiral Nagala at the time of the Cylon Holocaust. Other Fleet installations included the Scorpion Ship Yards, Ragnar Anchorage, and the Armistice Station.
Known Ships
By the time of the Cylon holocaust, the fleet included approximatley 120 battletars. Ships mentioned destroyed in that attack included Triton, Solaria, Columbia, and Atlantia, commanded by Admiral Nagala. According to Admiral Nelena Cain, two battlestars and three cruisers were destroyed in the Fall of the Scorpion Ship Yards.
Currently, the only two military vessels known to have survived the attack are the battlestars Galactica and Pegasus.
Notes
In the Mini-Series, William Adama tells Kara Thrace when she's released from the brig "We lost 30 battlestars in the opening attack". She responds, "That's a quarter of the fleet". This establishes that there were about 120 active battlestars at the beginning of the miniseries.