Working with the Rangers, Michael Garibaldi arranged for a former member of IPX, Dr. Mary Kirkish, to come aboard Babylon 5. Dr. Kirkish told the Army of Light about a Shadow vessel that was found on Mars in 2253. The ship was recovered by another Shadow vessel and Kirkish was reassigned, ordered not to say anything to anyone about what she had seen. Another ship was discovered on Ganymede just prior to the battle, which Earthforce was planning on reactivating within a week. After making arrangements for Kirkish to go to Minbari space, Delenn and Sheridan formed a plan to destroy the Shadow vessel before it could come online. Leaving his uniform and all identification behind, Sheridan captains the White Star with Delenn and Lennier on a mission towards Earth.
The Shadow vessel was activated when a human entered the vessel and was absorbed into its CPU. However, because the subject had not been prepared properly, the Shadow ship went insane and attacked the facility and everything in sight. Determined to stop the ship before any more damage could be done, Sheridan ordered the White Star to open fire on the Shadow vessel. The White Star blasted off one of the Shadow vessel's limbs, provoking it into giving chase.
Sheridan then lured the Shadow vessel into the gravity well of Jupiter. The White Star was able to pull up in time, but the Shadow vessel was trapped and destroyed by the pressure. Before the Whites Star could clear Jupiter's atmosphere, however, it was fired upon by the EAS Agamemnon, Sheridan's old ship. The Agamemnon, thinking they were behind the attack on Ganymede, demanded their surrender. Sheridan refused to fire on his old ship, and instead, performed another risky move: Opening a jump point inside Jupiter's atmosphere. Despite the dangers, the White Star pulled this off successfully and escaped into hyperspace.
The mission succeeded in destroying the Shadow ship and evading capture, though not before the ship inflicted heavy damage on Ganymede. ISN reported the incident as an "unknown alien ship" being destroyed after launching an unprovoked attack on the colony, though the White Star is blamed for the attack. ISN reported that President Morgan Clark declared Martial law due to this incident.