Wing Commander: The Secret Missions is the name of a stand-alone game port of the Wing Commander I add-on of the same name. It was retooled to be its own game, including a new intro cutscene, new manual, and a few other new features. It dates the game at 2656.289.
From the manual: In the Distant Future, Mankind Is Winning A Deadly War Against The KIlrathi in The Vega Sector
FROM: CONFEDHICOM -- ADM. DEKE STOVER TO: TCS TIGER'S CLAW -- COL. PETER HALCYON YOU ARE HEREBY ORDERED TO DIVERT FROM YOUR CURRENT POSITION IN VEGA SECTOR TO THE GODDARD SYSTEM, GODDARD II. FURTHER ORDERS TO FOLLOW UPON ARRIVAL AT COLONY. ALL COMMUNICATION TO ADDRESS MISSION AS "OPERATION THOR'S HAMMER."
Thus begins another chapter in the annals of the TCS Tiger's Claw. You have been ordered to the site of a crushing Kilrathi attack on a human colony. Intelligence indicates that the Kilrathi fleet is testing its latest secret weapon in this sector. You must pursue the warriors of Kilrah across enemy lines, destroy them, and eliminate the threat of their deadly new weapon.