It played a notable role in the Second Battle of Tiamat under the command of Vice Admiral
Frederick Jasper, destroying both the Kartenborn Fleet and then the Kosel Fleet. The fleet was dispatched to the front during the Third Battle of Tiamat as part of Alliance reinforcements, but did not arrive until after the battle. Its appearance at the front played a role in the Imperial withdrawal from the Tiamat starzone.
During the Battle of Astarte, the 4th Fleet consisted of 12,000 ships under the command of Vice Admiral
Pastoll. It was completely routed at Astarte by
Reinhard von Lohengramm's Imperial Fleet, being outnumbered and separated from its allies. After the battle, the survivors were amalgamated into the newly formed 13th Fleet.
