On September 24, 2669, Colonel Christopher Blair launched his successful Temblor Bomb strike on Kilrah. Its resulting blast wave took out the Emperor and Prince Thrakhath's enormous invasion fleet massing in orbit. The crown prince himself was also bested in combat just prior to Blair's descent to the planet's surface. Faced with this unfathomable loss, Thrakhath's chee'dyachee Melek immediately surrendered. VK Day was patterned after VE and VJ Day celebrated on Earth after World War 2. False Colors was the first to give us a name for the event in the WC universe. Also of note, Star*Soldier mentions VN Day, which strongly suggests that some significant victory over the Nephilim was also achieved by the year 2701. You can read about other major holidays in the Wing Commander universe here. Also don't miss Dundradal's historical comparison between VJ and VK Days here!
...Colonel, later Commodore Christopher Blair dropped the Temblor Bomb on Kilrah, destroying the planet. Soon after the Terran Confederation and Empire of Kilrah signed the Treaty of Torgo, know to the Kilrathi as the Treaty of Ko-bar Yagar, on the deck of the TCS Victory in the Torgo system. The Kilrathi had actually captured the system from the Confederation following the loss of the TCS Behemoth.
Much like the ceremonies on the USS Missouri and an unnamed frontier base, a simple table was the only furniture. Baron Melek, retainer to the deceased Prince Thrakhath, signed for the Empire of Kilrah. Crown Prince Thrakhath had been killed by Christopher Blair during the raid of Kilrah. Admiral Tolwyn signed for the Terran Confederation. Again the Terrans had a large delegation while the Kilrathi brought only a few. A flyby by four Hellcats took place at the end of the ceremony. The war was over.