William Hague served as an officer in the Earth-Minbari War. After the war, he continued to rise up through the ranks. After his reelection in 2258, President Luis Santiago appointed Hague Chairman of the Joint Chiefs-of-Staff.
In January 2259, following the death of Santiago aboard Earthforce One, Hague conveyed orders from the new president, Morgan Clark, to Captain John Sheridan of the EAS Agamemnon. Hague was delighted that Clark chose Sheridan, knowing him to be someone he could trust. Sheridan was being reassigned as the new commanding officer of Babylon 5. Hague then relayed the news to Lt. Cmdr. Susan Ivanova, acting command officer of the station.
Gen. Hague confided in Sheridan his distrust of President Clark upon his reassignment. He asks him to investigate the command staff for any sign of disloyalty. Several months later, he arranged to come to the station to debrief Sheridan on anything he had learned. However, while on patrol just prior to Hague's arrival, Sheridan was abducted by the Streib. When only one of Sheridan's escort fighters came back alone, Hague began to coordinate a search and rescue operation with Cmdr. Ivanova. He called in the Agamemnon to assist, and with information from Minbari Ambassador Delenn, Sheridan was rescued from the Streib. After being treated for minor injuries, Sheridan met with Hague privately. He stood by the commander officers' loyalty. Hague speculates that Clark was behind the death of Santiago, and that Psi Corps may be ultimately responsible. After reaffirming his full confidence in Sheridan, Hague suggests Sheridan bring in his staff to help pool the resources they need to restore EarthGov.
Hague was off Earth when President Clark declares martial law in 2260. After he dissolves the Senate and orders the bombing of targets on Mars, Hague abandons all intentions of returning to Earth. He is able to escape the Sol system on board the EAS Alexander. Within a day or two, however, most of the Earthforce ships that defected with Hague were hunted down and destroyed.