William The Conqueror was one of the four frigates that accompanied Griffin to the Coyote system, to assist in the rescue of the White Knights and the salvaging of the ATAFs. During the battle over Mythos, it was assigned to fighting up field with Ragnar.

After the allied forces' defence line collapsed and more of their forces were pushed back, William was moved to the defence of Sol.

After Elliott Parks decided to hijack Cratos to go in search of the prototype TSB, William, along with several other warships, made an attempt to stop the dreadnought from leaving the system. William was remotely disabled by Parks before it could do so, Parks applying the same method of handicapping the vessel as had been used against Ifrit in the Phylent system.